This sounds like a bad diode or a diode that became disconnected. Whenever power goes where it shouldn't, that's a diode issue. Nearly the same thing happened to my Jurassic Park.
I found this video that helped me fix the problem. In this video, if two switches are pressed at the same time, the switch in the scoop would trigger and kick a fantom ball.
Which sounds exactly like what's happening in your game, does it not?