I owned one in the past. Fun game, the spinner can be your best friend or your worst enemy.
To start off, try changing the state of the game over relay and see if that stops the score motor. It's a latch/trip relay, just flip it to the other state and see what happens.
After that, just start checking switches and relays. This game has steppers that need to be operational or, like all EMs and steppers, it will never work properly.
Mine had a near mint playfield and a pretty nice cab. The backglass was trash but I got a repro made. It was non working, I got it for $75 and had it working in a few days.