S**t sorry mate - didn't see this.
The position of the opto "interrupter" plate on the shaft is stupidly critical. If the plate can rotate on the shaft - the thing will hang up full-left. I could get 2 or three games before it would die - resetting the machine would make it work again.
I glued mine on the shaft while holding it in the right position (think I went counter-clockwise as far as it would go) - has worked ever since.
Hope that makes sense.
