By the way, this might also apply to the Bally Camelot as well.
I've been breaking my head over a small part of this pinball's schematic, so maybe some one can set me straight.
In the top left-hand corner of the playfield, there is an Extra Ball Alley. It contains a Normal Open roll over button (EXTRA BALL ALLEY ROLL OVER) and there is a Normal Closed switch in the one-way rebound gate (EXTRA BALL ALLEY REBOUND GATE). These switches are wired in series, see schematic detail.
When you send the ball through this alley it hits the roll over, which closes the circuit. By the time the ball has passed the roll over, it may pass through the rebound gate and find its way to the top of the playing field, but by then the Roll Over will already have opened again - so it makes absolutely no sense to have a N.C. switch in the gate to open and break the circuit. The ball cannot be physically opening the rebound gate and closing the roll over at the same time. Why is there a N.C. switch in that rebound gate?
"The schematics and the playfield are probably copyright by Bally." Used here for learning purposes only.