Need help with Nightmare on elm street. I have a location that wants the machine and I don't know that much on gottlieb machines.

Problems - Freddy mouth sometimes goes up/down for no reason but still works. Trap door needs adjusting as the ball can occasionally get stuck in the trough

Any help is appreciated

I'm going to go look at it tomorrow. I don't own the machine yet, but needed to know what I'm getting into. Hopefully it not major work.