Composite Door Wouldn't Lock – Complete Repair in One Visit

A customer contacted us because their composite door would no longer lock, leaving the property insecure.

On arrival, the fault was immediately apparent. The door handles simply hung limp when operated and lifting the handles produced no movement from the multipoint locking points. The latch was also missing, indicating that the locking mechanism had been deteriorating for some time and previous faults had been left unresolved.

After diagnosing the problem, the exact type of multipoint locking mechanism was identified before the complete mechanism was carefully removed from the door for inspection.

The centre gearbox had failed and required replacement. Once removed, the gearbox was replaced with the correct unit.

Rather than reinstalling the mechanism immediately, the locking strip was fully inspected. The locking hooks were stripped down individually, cleaned to remove old grease and debris, lubricated with the appropriate lubricant and reassembled. This ensured every locking point moved freely and reduced unnecessary strain on the new gearbox.

The serviced mechanism was then refitted to the door and tested.

Further inspection showed the door handle spring cassettes had also been damaged, preventing the handles from returning correctly. New spring cassettes were fitted, restoring proper handle operation and ensuring the levers returned smoothly to the horizontal position after use.

With the locking system operating correctly, the final stage was to eliminate movement between the door and frame. The keeps were carefully adjusted so the door closed firmly without rattling while still allowing the handles to lift effortlessly. Correct adjustment also ensured the weather seals compressed evenly, creating a proper seal around the entire door.

The complete locking system was thoroughly tested several times. The handles lifted smoothly, every locking point engaged correctly, the key turned freely and the door locked and unlocked exactly as it should.

The customer tested the door themselves before we left and was delighted that it had been fully repaired during a single visit.

Work Carried Out

• Diagnosed composite door locking fault.
• Identified the correct multipoint locking mechanism.
• Removed the complete locking mechanism.
• Replaced the failed centre gearbox.
• Stripped down, cleaned and lubricated the locking hooks.
• Reassembled and tested the complete mechanism.
• Replaced damaged handle spring cassettes.
• Adjusted the frame keeps to remove door movement.
• Improved weather seal compression.
• Fully secured, tested the locking system and door operation.
• Completed the repair in a single visit.

A thorough diagnosis and repair of the complete locking system restored the door to full working order without the need to replace the entire multipoint mechanism or the door itself.

Conclusion

A faulty door mechanism doesn't usually mean you need a new door. In many cases, the damaged gearbox or multipoint locking mechanism can be repaired or replaced while keeping your existing door and frame. Even if the door is jammed shut, it can often be opened without replacing the door, allowing the faulty gearbox or mechanism to be repaired. This guide explains when repairs are possible, why obsolete mechanisms can often still be repaired or replaced, the importance of correct door alignment, and how an accurate diagnosis can save homeowners from the unnecessary expense of replacing an otherwise perfectly good door.