I made some quick notes while investigating what happens when the ball drains. They were useful for me in figuring out that last issue, so figure I should keep them here...
A: BALL RETURN CONTROL RELAY
E: BONUS SCORE RELAY
O: BALL RETURN RELAY
P: ADD PLAYER UNIT RELAY
Ball enters trough.
This activates/latches P when, motor is at 1C
P activates the motor.
A is active when there are bonuses out there, and activates E so bonus can count.
at end of Bonus counting, we get to 4th position on bonus unit realy, 8B opens, so A deactivates
O can then activate once A toggles back to inactive, and motor 1C
O activates the ball return coil when Motor 4C.