I have a Williams Solids N Stripes that is having a problem with one player games. Everything works as intended, including the one-player light on the backglass, except for the ball stepper. It is only stepping once instead of twice for one player games. If I play a two player game, everything works fine as the stepper continues to step one time. I thought it might be a problem with the 2nd coin relay, but that seems to be working okay (will switch to a two player game without difficulty when unlatched). What determines if the ball stepper steps once or twice? Thanks for any help you can provide.