Overview
A composite door that suddenly refuses to lock is one of the most common problems we're called out to in Cornwall. In 9 cases out of 10 it's either a keep alignment issue (the door has dropped and the hooks miss the frame plates) or a failed multi-point gearbox. Both are fixable, often the same day.
Symptoms
- Handle won't lift, or lifts partway and jams.
- Handle lifts but the key won't turn afterwards.
- Loud grinding or clunking as the hooks try to engage.
- You can lock it when open but not when the door is closed against the frame.
Common causes
- The door has dropped on its hinges and the hooks miss the keeps.
- Multi-point gearbox has failed internally.
- Keeps on the frame have worked loose or shifted.
- Debris or a bent hook fouling the mechanism.
- Weather seal has swollen and is holding the door off the frame.
When to call a professional
- The multi-point mechanism no longer engages when you lift the handle.
- You can see or feel a broken hook, roller or cam inside the door edge.
- The key turns but the door stays locked, or you are locked out.
- Recent forced-entry attempt or visible damage to the cylinder.
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.