start by stating what problem you have.....is it totally dead? There is a on/off switch and there is an interlock switch on the back door and I think there is one on the coin door as well. They have a white rod that sticks out that activates when the door is closed. Gonna need more info about what works and doesn't.
I clocked asteroids in one of the seafront amusement arcades back in the 1980s. Each game was 10p a shot. Eventually could make 10p last for over an hour of game time. Not sure if I still got the magic though.