I wish it was that but the problem is that when you move the focus ring the front assembly doesn't move in or out of the body of the lens anymore, so it's a mechanical problem rather than electrical.May be stating the obvious, but have you tried cleaning the contacts with a pencil earazer? It may be that the contacts have become dirty, although I don't know why manual focus would be affected.
Thanks Bob - I did find a guide online for this and it looked pretty simple - what stopped me was that I was worried about was changing the lens focus accuracy when I put it back together as I don't have a way to collimate it accurately. Do you know if this is a valid concern or am I worrying about nothing?It sounds like the focussing helicoil cam follower has broken. This is under a fair deal of stress if the lens if stored with the barrel extended (the infinity focus end IIRC). It should be a quite simple fix if you can get the part ordered....YA2-1776 or YA2-1777 at a guess.
When you get it sorted, remember to store it with the focus set somewhere in the middle of its range.
Bob
I'm going to hazzard a guess that nothing should change as I don't believe that you'll need to go so far that any registration will change....famous last words though.....I did find a guide online for this and it looked pretty simple - what stopped me was that I was worried about was changing the lens focus accuracy when I put it back together as I don't have a way to collimate it accurately. Do you know if this is a valid concern or am I worrying about nothing?
Flats said:This lens is prone to focussing problems, always has been. I managed to kill one years back, it is simply too delicate, which is basically, as I see it, a design fault. Rubbish.
I do that when I take out my backpack, but quite often I use a smaller shoulder bag and it doesn't fit. Hmm.. maybe I should just get a bigger bag...I leave mine in the bag with the hood in situ, non reversed.

That's exactly what I'd have said a week agoI just chuck mine in the bag & it's been fine.