Mortise Lock Repair and Installation in Newmarket
What is inside a mortise lock body, when it can be rebuilt instead of replaced, how the cylinder and cam have to be sized, and how to modernise a mortise-prepped door without wrecking it.
Quick answer
A mortise lock is a rectangular lock body buried in a pocket cut into the edge of the door, driving both a latch and a deadbolt from one case. Mortise lock repair in Newmarket usually means stripping and rebuilding the body, replacing worn springs, the hub or the cylinder, rather than replacing the whole unit, which is often far more expensive.
A mortise lock is not a lock that sits on a door. It is a lock that lives inside one. Somebody cut a deep rectangular pocket into the edge of the door slab, dropped a steel case into it and screwed a faceplate over the top. Everything happens inside that case: the latch, the deadbolt, the handle hub, the springs, the cylinder linkage.
That construction is why mortise locks last for decades and why the good ones outlive three or four cylindrical locksets. It is also why they cannot be swapped casually. The pocket is a specific size, the faceplate is a specific shape and the holes through the door face are in specific places. Buy the wrong body and you are looking at woodwork, not hardware.
We repair and install mortise locks across Newmarket, from the century houses near Main Street South and Fairy Lake to the glass storefronts along Davis Drive and the older commercial units off Mulock. Below is what actually goes wrong in these locks, when a rebuild beats a replacement, and what the retrofit path looks like if you want modern hardware on an old door. For general hardware failures on newer doors, see lock repair.
What is inside a mortise lock body
Once you know the parts, the symptoms tell you which one has failed.
Take the cover plate off a mortise case and you find a surprisingly busy little machine. Everything is stacked into one steel box roughly six inches tall by four deep.
The hub and spindle
A square hole in a rotating hub that the handle spindle passes through. Turning the handle rotates the hub, which pulls the latch back. Two hubs on a double-handle lock, one for each side, sometimes independently sprung.
The latch and its spring
The angled bolt that lets the door close. A coil or leaf spring pushes it back out. When a handle goes floppy or the latch stops springing back, this spring is nearly always the culprit.
The deadbolt and its lever pack
A square-ended bolt driven by the cylinder cam or the thumbturn, usually through a stack of levers or a simple rack. This is the part doing the actual securing.
The cylinder and cam
A threaded mortise cylinder screws in from the outside face and its cam sits inside the case. Turning the key turns the cam, which drives the bolt or, on a storefront lock, retracts the latch as well.
Common failures follow a pattern. A handle that droops and will not spring back is a hub or latch spring. A key that turns but nothing moves is usually a cam that has come loose, a snapped tailpiece or a broken lever. A deadbolt that throws halfway and stops is either a broken part inside or, more often, the door has dropped and the bolt is hitting the strike. A lock that has become gritty and stiff is asking to be stripped and cleaned before it breaks properly.
Why Newmarket still has so many mortise locks
Two reasons, and they are different reasons. The first is age. The older housing stock around Main Street South, Quaker Hill and the streets running down towards Fairy Lake dates from an era when a mortise lock was simply how a front door was locked. Many of those doors are original, thick, solid and worth keeping. The lock in them may be eighty years old and still working, because there is very little in a mortise case that wears out quickly.
- Century and pre-war houses in central Newmarket, often with original hardware worth preserving
- Aluminium storefront doors on Davis Drive, Yonge Street and the Mulock plazas
- Older apartment and walk-up entrances, frequently paired with a rim or jimmy-proof lock
- Institutional doors, offices and back-of-house entries in commercial units
- Some heritage-styled new builds where the architect specified mortise hardware for the look
The second reason is commercial. Aluminium and glass storefronts, the ones you see along Davis Drive, Yonge Street and in the plazas off Mulock, are almost universally mortise. So are a great many institutional and multi-tenant doors. In a commercial setting the mortise lock earns its place because one case can carry a lever, a deadbolt, a hold-back function and a high security cylinder, and because it takes hundreds of cycles a day for years. Commercial mortise work usually arrives alongside door closer adjustment or a panic bar on the neighbouring leaf.
Rebuild the lock body or replace it
The honest answer depends on what is broken and what the case is worth.
A mortise body is a repairable object, which sets it apart from most modern hardware. Springs, hubs, latch bolts, deadbolt tailpieces and cover screws are all replaceable parts, and on the major commercial makes they are still available. On a domestic case from the 1920s the parts may not be, but the tolerances are loose enough that a competent locksmith can often fabricate, re-tension or substitute.
| Symptom | Usual cause | Rebuild or replace |
|---|---|---|
| Handle droops, latch does not spring back | Broken or fatigued latch spring, worn hub | Rebuild. Spring and hub work is the most common mortise repair there is. |
| Key turns freely, nothing happens | Cam has loosened, tailpiece snapped, lever broken | Rebuild if parts are available, otherwise replace the body. |
| Grinding, gritty, stiff throughout | Decades of dust and dried lubricant inside the case | Rebuild. Strip, clean, re-lubricate dry, reassemble. |
| Deadbolt throws part way | Nine times out of ten the door has dropped and the bolt is fouling the strike | Neither. Realign the strike and check the hinges first. |
| Case is cracked or the faceplate is torn | Forced entry damage or a very old casting | Replace the body, and check the door edge for damage repair at the same time. |
| Lock works but you want modern security | Nothing is broken | Change the cylinder, not the lock. Far cheaper and no woodwork. |
A rebuild is normally the cheaper route and it preserves original hardware. Replacement makes sense when the case itself is damaged, when parts genuinely no longer exist, or when a commercial door needs a current-standard lock for code or insurance reasons.
Handles, spindles and cylinder sizing
Two areas cause more wasted parts orders than anything else on mortise work. The first is handling. A lever or knob is driven by a spindle passing through the hub, and the spindle has to be the correct square section and the correct length for the thickness of the door. Too short and the handle will not sit tight against the escutcheon, too long and it bottoms out and binds. Set screws work loose over the years, the lever starts to have play, and eventually the spindle rounds off the hub. A wobbling lever is a warning that should be dealt with before it strips.
- Measure a mortise cylinder from the shoulder to the back of the threaded body, not overall including the cam
- The cylinder should finish flush with the escutcheon ring, with the ring taking up any small difference
- Cam shapes are not universal. A cam that fits one manufacturer will sit at the wrong clock angle in another
- On a rim-cylinder lock the equivalent part is a flat tailpiece, cut to length on site with a hacksaw
- If you are upgrading to a restricted key, the cylinder is the part that changes, not the lock body. See high security locks
- Spindles should be replaced rather than shimmed once the square has rounded over
The second is cylinder sizing. A mortise cylinder is threaded, and it screws in until its cam sits in the right place inside the case. Get the length wrong and one of two things happens. Too long, and the cylinder protrudes past the escutcheon leaving a nose to grip and twist. Too short, and the cam never reaches the drive, so the key turns and the bolt does nothing. Mortise cylinders come in quarter-inch steps and the cam shape has to match the lock make as well.
Retrofitting a mortise-prepped door without ruining it
The pocket is already cut. That is a constraint, and also an opportunity.
People often want to move from a tired mortise lock to a modern deadbolt and handleset. It can be done well, and it can be done in a way that permanently spoils a good door. The difference is whether you work with the existing preparation or against it.
First choice: a modern mortise body
Current commercial mortise locks from the main makers are built to a standard case size that fits most existing pockets. You get a Grade 1 lock, a lever that meets accessibility expectations and a modern cylinder, and the only visible change is the faceplate and trim.
Second choice: change only the cylinder
If the body still works, fit a new mortise cylinder with a restricted or high security keyway. The door is untouched, the appearance is unchanged and the security jump is real.
Third choice: a conversion plate
If you truly want cylindrical hardware, a mortise conversion plate covers the old pocket and the old face holes and provides fresh bores for a deadbolt and a knob or lever. Done properly it is tidy. Done badly it is a bent piece of tin over a hole.
Last resort: filling the pocket
Gluing a hardwood block into the mortise and re-boring is possible on a solid timber door, but it is joinery, it takes time and the repair will be visible on the door edge. On a heritage door we would talk you out of it.
On a century home the honest advice is usually to keep the mortise lock and upgrade the cylinder. The door was built around that lock. On a commercial unit where the lock is failing under daily use, a modern Grade 1 mortise body is the right answer and it drops straight in. If the whole entrance needs rethinking rather than repairing, see commercial lock change.
Mortise lock prices in Newmarket
Mortise work is more labour than parts, because the case has to come out, be opened and be reassembled correctly. These are typical 2026 ranges for Newmarket and the surrounding towns.
| Job | What it covers | Typical price |
|---|---|---|
| Mortise lock service and adjustment | Strip, clean, re-lubricate, reset springs, realign | $140 – $240 |
| Mortise lock rebuild | New springs, hub, latch or bolt parts where available | $200 – $360 |
| Mortise lock body replacement | New body fitted into the existing pocket, faceplate adjusted | $280 – $520 |
| Mortise cylinder replacement | Correct length and cam, escutcheon ring, keys | $120 – $220 |
| Lever or knob and spindle repair | New spindle, set screws, trim refit | $110 – $190 |
| Mortise to modern hardware retrofit | Conversion plate or new prep, deadbolt and handleset | $300 – $650 |
Ranges are typical for Newmarket in 2026 and cover parts and labour on a standard door. Overnight, weekend and statutory holiday call-outs carry a premium. A firm price is confirmed on the phone before anyone is dispatched.
Why Newmarket calls us first
Mortise lock work across Newmarket and the surrounding towns
Mortise calls cluster in two places: the older residential streets in central Newmarket and around Fairy Lake, and the commercial strips along Davis Drive, Yonge Street and Mulock Drive. We cover both, and the same service runs out to the neighbouring towns.
Frequently asked questions
What is a mortise lock?
A lock housed inside a rectangular pocket cut into the edge of the door, rather than fitted through round holes in the face. One steel case carries the latch, the deadbolt, the handle hub and the cylinder linkage. It is the standard on older houses and on almost all commercial aluminium storefront doors.
Can a mortise lock be repaired or does it have to be replaced?
Most can be repaired. Springs, hubs, latch bolts, cams and spindles are replaceable and are the parts that actually fail. A rebuild typically runs $200 to $360 against $280 to $520 for a new body, and it keeps original hardware on an older door. Replacement is the right call when the case is cracked, when parts no longer exist, or when a commercial door needs a current-standard lock.
Why has my mortise handle gone floppy?
A broken latch spring or a worn hub inside the case, or a spindle set screw that has worked loose. It is the single most common mortise fault and it is a repair, not a replacement. Left alone the spindle eventually rounds off the hub, which turns a cheap fix into an expensive one.
My key turns but the bolt does not move. What is that?
The cylinder is turning but not driving anything. Usually the cam has loosened on the back of the cylinder, the tailpiece has snapped, or a lever inside the case has broken. Occasionally the cylinder is simply the wrong length and the cam never reaches the drive. All are fixable without touching the door.
How do I measure a mortise cylinder?
From the shoulder under the escutcheon ring to the back of the threaded body, ignoring the cam. They come in quarter-inch steps. The cam shape must match the lock manufacturer as well as the length, since an identical-looking cam can sit at the wrong clock angle and never engage.
Can I put a modern deadbolt on a door that has a mortise lock?
Yes, but consider the alternatives first. A modern Grade 1 mortise body usually drops into the existing pocket and gives you current hardware with no woodwork. A new high security cylinder in the old body gives most of the security benefit for a fraction of the cost. A conversion plate is the fallback, and filling the pocket is a last resort we would talk you out of on a heritage door.
Do you fit high security cylinders to mortise locks?
Yes. It is one of the best upgrades available on an older door, because you get restricted keys and drill and pick resistance without altering the door at all. The full framework for deciding is on our high security lock upgrade guide.
Do you do commercial storefront mortise locks?
Regularly. Aluminium storefront doors on Davis Drive, Yonge Street and the Mulock plazas run mortise hardware, and they take heavy daily use. We service and replace the bodies, fit high security or master keyed cylinders and adjust the door closer at the same visit so the lock is not fighting the door.
Related locksmith services in Newmarket
Get the mortise lock opened up and diagnosed properly
Describe what the handle or key is doing and we will usually know which part has gone before we arrive. Call 866-820-1331, 24 hours a day, every day of the year.
