Yep it sets up properly for a game start, provided you don't have the ball in the launch trough.

ie score reels reset to zero, ball counter unit goes to pos 0 (game start). By my terminology 1-5 are balls in play, 6 is game over.

So, keep ball out of it, have a credit available, press game start on coin door and everything goes to "good" positions.  Score motor is stopped at this stage.

Now place ball in, closing the switch at the launcher and it fires through every ball in play on the ball count unit and finishes at game over. The ball launch solenoid never fired in this sequence.  (by other means we verified that the ball launcher can fire) So at this stage the score motor just keeps running - it stops at game over I'm prteyy sure. (Rob, is that how you recall it?)

I've been looking at the schematic today and coming up with a test strategy. Some of it is as you are alluding to I think Daniel. ie what contacts drive the score motor - unfortunately lots!  W, C, D, G, P, S, U, V AB and 1C  But it's a staring point.