A customer contacted us because their uPVC door had become impossible to lock. The handle would lift, but the multipoint locking mechanism would not fully engage, leaving the property insecure.
Our initial inspection found that the gearbox had failed, which is a common fault on older multipoint locking systems. The gearbox was removed and replaced with a new matching unit.
However, after fitting the new gearbox, the mechanism still wasn't operating correctly.
Rather than assuming another part was faulty, the complete locking strip was removed for further inspection. This revealed that the top locking hook had seized internally. Years of dirt, dried lubricant and wear had prevented the hook from moving freely, causing excessive strain throughout the mechanism. This extra resistance had almost certainly contributed to the gearbox failure.
The seized hook assembly was carefully dismantled, thoroughly cleaned to remove built-up debris and old grease, then inspected for wear. As the components were still in good condition, they were lubricated with the correct lubricant, reassembled and tested before being refitted to the door.
Once the locking strip was reinstalled, the gearbox and all locking points operated smoothly. The door was then fully tested, with the handle lifting easily, the key turning correctly and every locking point engaging and releasing as intended.
By diagnosing the complete mechanism rather than simply replacing parts, we were able to restore the original multipoint lock without replacing the entire locking strip, saving the customer the cost of a much larger repair.
Work carried out:
- Diagnosed multipoint locking fault.
- Removed complete locking mechanism.
- Replaced failed gearbox.
- Located seized top locking hook.
- Dismantled hook assembly.
- Cleaned and removed old grease and debris.
- Lubricated moving components.
- Reassembled and tested the locking mechanism.
- Reinstalled the mechanism.
- Fully tested door operation and locking performance.
The door now locks and unlocks smoothly, with all locking points operating correctly and without excessive force.
Related articles:
- Signs Your Multipoint Lock Mechanism Needs Attention.
- Should You Lubricate Your Locks.
- Can a Seized Hook Damage a Multipoint Lock?
