Quick answer
A multi-point lock not working means one or more of the hooks, bolts or rollers along the door edge has stopped engaging, even if the rest still function. This significantly weakens the door's security and can affect insurance validity. Watch the door edge as you lift the handle to identify which point has failed.
Overview
A multi-point mechanism engages 3-7 locking points down the door edge in one handle lift. When one or more stops working, the door is dramatically less secure - insurance will often refuse claims where the mechanism was known-faulty.
Symptoms
- Handle lifts but you can hear only some of the hooks engage.
- One hook or bolt visibly doesn't extend.
- Handle feels lighter than usual - no spring resistance.
- Door pushes open even with the handle up.
Common causes
- Broken gearbox - one output has failed while others still work.
- Broken drive-bar link between the gearbox and the hook.
- Bent hook after forced closing.
- Snapped internal spring.
How a multi-point system is meant to work
A single lift of the handle is designed to simultaneously drive three to seven separate locking points into the frame — a mix of hooks, shootbolts and sometimes rollers, all connected by a drive bar to one central gearbox. The strength of the system comes from this redundancy: even if an intruder attacks one point, several others are still holding the door closed.
When even one of these points silently stops working while the others continue to function, the door often still feels normal to use day to day — the handle lifts, the key turns, nothing obviously seems wrong. That's precisely what makes a partial failure more dangerous than an obvious one: you keep relying on security the door no longer fully provides.
Spotting a partial failure before it's tested by someone else
Open the door fully and watch the edge closely as you lift the handle. Each hook or bolt should extend at roughly the same moment with a consistent, firm action. A point that doesn't move, moves late, or extends only partially is the one that's failed.
A more subtle sign is a handle that feels noticeably lighter than it used to, with less spring resistance at the top of the lift — this often means one output on the gearbox has stopped driving its corresponding point, reducing the overall load the handle has to work against.
- Watch each hook/bolt individually as the handle lifts
- Compare resistance at the top of the lift to how it used to feel
- Test from both outside (key) and inside (handle or thumbturn)
- Check for a visible gap where a hook should be seated in its keep
What actually breaks inside a multi-point mechanism
The most frequent failure is a broken gearbox — not total failure, but partial, where one output shaft has sheared or worn while the others continue operating normally, since each point is often driven by a separate connection from the central unit.
The drive bar linking the gearbox to a distant hook (often at the top or bottom of the door) is another common failure point, particularly on taller doors, and a bent hook — usually from an attempted forced entry or a very hard slam — can also stop a single point from seating correctly even when the gearbox itself is fine.
Why insurers care about this specifically
Many home insurance policies specify that doors must be 'locked with all operable locking points engaged' as a condition of cover, and a partial mechanism failure can put you in a position where a claim is technically vulnerable to being challenged, even though the door appeared to be locked.
If you're aware a locking point has stopped working and choose not to have it repaired, that awareness is exactly the kind of detail an insurer's assessor will ask about following a break-in, so it's genuinely worth addressing promptly rather than treating it as a minor inconvenience.
PAS24 and what 'compliant' really means
New-build and rental properties are often specified with PAS24-rated doors, a standard that assumes the full multi-point mechanism is operating as designed. A door with a failed locking point is no longer performing to that standard, regardless of what rating was originally certified when it was installed.
For landlords and holiday let owners, this matters beyond personal security — some management agreements and certain insurance products specifically reference PAS24 compliance, and a known partial failure could technically breach those terms.
The repair itself
Fixing a partial mechanism failure usually means replacing the gearbox as a complete unit rather than attempting to repair a single output, since the internal components are generally not designed to be serviced individually. Where the fault is a bent hook or a snapped drive bar rather than the gearbox itself, a more targeted replacement of just that component is possible.
We always test every single locking point individually after a repair, both with the door open and firmly closed, because confirming the fix has genuinely restored full multi-point security — not just resolved the most obvious symptom — is the whole point of the visit.
How we isolate which locking point has failed
A multi-point system typically has between three and five locking points — usually a mix of hooks, rollers and a central deadbolt — and a fault in one doesn't mean the whole set has failed. On arrival we test each point individually where the door design allows, since a single seized hook can present exactly like a total gearbox failure to someone testing the handle alone.
This matters for cost: a single hook repair is a fraction of the price of a full multi-point set replacement, and rushing to condemn the whole mechanism without this individual testing is how customers end up paying for more than they need.
How a partial failure spreads to the whole system
Once one locking point binds or fails, the drive bar connecting all the points has to work around that resistance every time the handle is lifted, putting uneven strain on the gearbox and the remaining points. Left unaddressed, a single failed hook commonly takes the whole mechanism down with it within a matter of months.
This is why a 'minor' single-point fault reported early is genuinely worth fixing promptly — it's one of the few door faults where early intervention has a clear, quantifiable cost benefit rather than just being good practice.
Coastal corrosion inside sealed mechanisms
Multi-point gearboxes are sealed, but not hermetically — condensation and salt-laden humidity do find their way in over years, particularly on doors facing prevailing weather along exposed stretches of coastline from Newquay round to the Roseland. Once corrosion starts on the internal steel components, it tends to progress faster than equivalent wear inland, because the corrosion itself creates friction that accelerates further wear.
We've opened up gearboxes on ten-year-old coastal doors to find visible surface rust that an equivalent inland installation simply wouldn't show at the same age.
What we check before quoting on this fault
Before quoting we'll check whether the drive bar itself is intact, since a bent or disconnected drive bar can mimic a multi-point failure while actually being a much simpler and cheaper fix than replacing the gearbox and all associated hardware.
We also check keep alignment at every locking point along the frame, not just the main lock, because a single misaligned keep partway down the frame is a common and easily-missed cause of a system that seems to fail intermittently across multiple points.
Describing a multi-point fault accurately on the phone
Tell us whether all locking points seem affected or just one area of the door (top, middle, or bottom), and whether you can see or hear a specific point not moving when the handle is lifted with the door open. This detail alone often lets us bring the exact right part rather than a full replacement set on spec.
Typical repair costs in Cornwall
| Work | Typical price | Notes |
|---|---|---|
| Diagnostic visit and point-by-point testing | £45-£85 | Identifies exactly which point has failed |
| Gearbox replacement (restores all points) | £180-£320 | Most common fix for partial failures |
| Single hook or bolt replacement | £75-£150 | Where only one component, not the gearbox, has failed |
| Drive bar replacement | £90-£160 | Common on taller doors with remote locking points |
Guide prices only — we confirm the cost after seeing the door.
When to call a professional
- Any point that isn't engaging.
- The door is no longer PAS24 compliant without a working mechanism.
Prevention
- Lubricate the cylinder twice a year with a graphite or PTFE lock spray - never WD-40 or oil.
- Grease the hooks and rollers on the door edge every 6 months.
- Always lift the handle to engage the multi-point locks before turning the key - this takes load off the gearbox.
- Never force a stiff key - book a service call before the mechanism snaps.
