Dickydo,

All three of the saucers activate the bonus unit; the top saucer advances the bonus and the two side saucers count them down.

If the bonus unit is being activated but is not then sending the signal to kick the ball, one of the switches needs adjusting to insure that it is tight and closing.

With the game on, glass off, and the coin door open, drop a ball into a saucer and then look under the playfield. You should see the score motor running and making your "kerchunk".

Your schematics should help you trace the path from the saucers to the bonus unit and then score motor. Tighten all switch stacks, lightly run some emory cloth between the swithes and adjust as necessary.

Good luck!