If I move the bonus unit under the playfield by hand, the bonus unit will reset when you press start for a new game. The bonus unit moves back and forth freely.
That sounds positive but you need to ensure that zero position contact on the bonus unit is making a closed circuit when a ball is in play to the out hole switch. This would be easy to check with a multimeter. Or you could easily make your own.
4 x 6 volt globes wired in series makes a 24 volt indicator, twist one end around the black common of the bonus RE and the other around the green wire on the out hole switch. This will prove if power is coming from the bonus unit to the out hole switch during a game. Maybe someone with a more detailed knowledge of the bonus unit can guide you to the zero position switch.
