The drive will not boot, if all of your 6522's are defective. There must be some life in some of those chips,
because your drive does boot up.
Yes, both drives boot, both show the exact same issue, the head attempts to move but there's just a faint vibration & sound rather than the head actually moving.
I've tried every combination of the 6522's in a both drives and get the same result - which is why I think I've fried UC1 in my original working drive, and that this just happens to be the issue that the non working drive arrived with (I know I didn't misalign any connectors on that drive).
Thanks for the support though, it's much appreciated.
Incidentally, I swapped out the 9602 and that made no difference either.