According to the schematic - Switch 1C in the score motor is NORMALLY CLOSED from 0 - 15 Degrees - which is "mumbo jumbo" for you right now - But after the score motor has stopped running, 1C should be closed.. One wire will be a Blue/Black (from motor 4C and reset completed relay) , the other will be White/Black ( to Ball return control relay).
In english - looks like the 1C switch should be adjusted to be closed when the score motor is at rest - AFTER the game starts, and the score reels have all set to ZERO. The ball return switch should be closed for the coil to be pulled in on the Ball return control relay.
The score motor will advance to close switch 2C and the Ball Return Relay will be closed which fires the ball shooter coil...
I'd say you have found a problem, but not necessarily the solution - Yet !
