Overview
A jammed lock means something inside the multi-point mechanism has failed or a hook has caught on the frame. Forcing it usually shears the gearbox spindle - a repair that's five times the cost of catching it early.
Symptoms
- Handle stuck up or down and won't move.
- Key stuck partway through rotation.
- Door won't open even though you've unlocked it.
- Loud snap or click before it jammed.
Common causes
- A hook has caught behind its keep instead of dropping into it.
- Gearbox spring or cam has broken.
- Cylinder cam has sheared.
- Foreign object (a coin, a nail) has fallen into the mechanism.
When to call a professional
- Any resistance beyond a normal firm push.
- Key or handle stuck for more than a few minutes.
- Locked out entirely.
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.