As my previous thread when I had a similar problem of having to yank the handle and the door not locking, I asked if the two were related, they weren't. Ok the lock was knackered but the yanking of the door was caused by the handle operating rod being too short. Adjusted it and it was fine. Wondering why this should happen and the only answer I can think of is that the rod shortens itself by pushing thro the plastic connector to the lock. We shall see.