This was a bit of a hair puller, so I figured I'd post the solution in case someone else is searching for it. Have a 72 William's Fantastic that always started on a four player game, regardless of how many players were selected. The problem was in the rear stepper unit (in cabinet), someone jammed their fat fingers between the stepper fingers and slightly bent them so they weren't touching ground. The playfield needed to be removed to see the problem since it was all the way in back of the cabinet. We found two fingers bent up, so with a little finesse with some thin needle nose pliers the pins were bent back to their original shape and viola! The game starts and stays on how ever many players selected. Nice to be able to play one player when you want one player
Hope this helps someone else from going crazy!

I was thinking of posting solutions to some weird problems as we come across them. I know I search for solutions online when we can't figure something out, so I assume a thousand other people do the same thing. This one made no sense, so it really was a relief to fix it. Playing 20 balls per game gets old, fast!