ohhhh loved that game
sorry no clue on resolving your problem though :/
remember machines doing that as a kid and the only solution for the person working at the arcade was giving us some quarters and putting an 'out of order' sign on em :
This website might help you DIY it though
Arcade Repair Tips ? Fix The Game, Play The Game and their youtube
http://www.youtube.com/user/varcadegames