I repair these machines for a living around pittsburgh pa. The most likely cause of your problem is a bad membrame switch. its in the control panel. it also causes the pushed forward button machine ran backwards. the switch is easily replaced, costs under 20 bucks and while you have it apart clean the board contacts with electrical contact cleaner
feel free to call me, telephone help is always free
bob haller service and sales pittsburgh pa 412 366 4906, July 2012
