Went to a job today where the customer thought the lock on their UPVC door had broken as they could not move the handles down. We took the handles off to have a look at the mechanism in order to work out what was wrong. Nothing was immediately apparent as the cause of the problem. After opening the door the lock seemed to be working but was incredibly stiff. After lots of lubricant it started to free up and was working fine again. The lock was on a door which had not been opened for several years and had basically seized up through lack of use and not being lubricated. Customer was pleased that the final bill was less then the quoted price as no parts were required.