A customer in Addlestone got in touch because the mechanism on the garden sliding door would not engage, leaving the door unable to lock.
I had not worked on this exact brand of mechanism before, but after removing a considerable number of screws and exposing the internal workings, the problem became fairly obvious. The mechanism itself was not broken.
A tiny pin, only around 1–2 mm in diameter, had moved out of position. That small movement was creating a knock-on effect through the mechanism and preventing the whole locking sequence from engaging.
I repositioned the pin, checked the moving parts, worked the mechanism through its full travel, reassembled everything and tested it repeatedly. I also showed the customer what I had found and what I had done, so he understood the cause of the fault if the same issue ever appeared again.
A very small displaced part had managed to stop an otherwise serviceable sliding-door mechanism from working at all.
