A local customer in Ashford called because the front-door nightlatch was becoming increasingly difficult to operate. The key would sometimes take several minutes of trying before it finally turned.
Copied keys can sometimes accelerate wear inside a cylinder, but that was not the explanation here. The customer had both the original working key and an original spare, and both behaved in exactly the same way.
The backbox itself appeared to be in good working order, so the rim cylinder became the main suspect.
I removed it and gave it a thorough clean and lubrication. A surprising amount of black contamination came out, and after cleaning the cylinder appeared to operate perfectly.
I refitted it and left hoping the problem had been solved.
Unfortunately, the following day the customer called to say the same fault had returned.
At that point there was no value in continuing to experiment with an unreliable cylinder. I returned, removed the old rim lock and fitted a new replacement.
The key operation was then smooth and consistent again.
