I am most grateful for your reply (the only one so far). A complete, known-good, engine would be fantastic. Only problem is the I am in the UK!! (What would the shipping cost???!!) Hence the problem, as there are almost no 750A's over here. I have two "normal" 750's and thought it would be nice to complement the collection with an unusual "A". I have been asking some US breakers if they would check the function of the part in question. I would buy a complete gear set (as they won't split one) if I knew the one they have works as I think it should. Sadly, they don't seem willing to assist in doing that check, before I send them the cash.
I don't mind paying for what I need - I just would prefer not to buy something that won't fix the problem.
Thanks, once again.
Rod