Been to two jobs in the last couple of days where the door or window wouldn't close and both customers thought it was the lock that was at fault. In both cases the lock was catching on the frame of the door or window and preventing it closing. However the reason this was happening was due to the door and window both having 'dropped' from their correct position. In the case of the window it required 'heel and toeing' to bring it back into line with the frame. The same was done to the door and the hinges adjusted as well. In both cases the repair were fairly quick and cheap as no parts were needed. As you can see sometimes locksmiths never even touch the lock.