If the ball goes into the hole under the skull and doesn't eject from the lower-right scoop, it could possibly be one of the following: (1) the switch in the tunnel under the skull; (2) the coil that ejects the ball; (3) a fuse; or (4) the transistor that controls the coil that ejects the ball from the lower-right scoop. To diagnose, I would put the game in switch test mode and check the tunnel switch. Then, put the game in coil test mode and check the coil that ejects the ball. Depending on what you find, this should at least get you started in the right direction.

It sounds to me like the machine is booting. Otherwise, you wouldn't hear "bad ball" when pressing the start button. That means the game is not in free play and there are no credits. Try adding a credit and see if you can start a game.

_{Post edited by gseador : typo}