Hmmmmmmm not so actually they have gone mental again!!!!
Hi
Mine used to do that,When the screen was wet they were ok as the screen dried a bit they used to stop were they liked.
Cured problem a new motor from Island 4x4 good price and those spring clips to take up any play in linkage it only takes about half hour to fit now everything works ok and is very quiet.
Thanks I gave it a shot tonight to have a play with the linkage but no joy so it's a new motor I think. Seen one on eBay new for £45 is that a decent price?