When the “B” relay is tripped and the ball drains the game scores endlessly, the bonus unit is not being pulsed to count backwards. However if the “A” relay is tripped and the ball drains it works as it should. And if both “A” and B” activating double bonus are tripped, it works as it should when ball drains. I cannot follow the schematics to figure out which possible switch may be the culprit for when only the “B” relay is only tripped and ball drains, to allow bonus unit to count backwards. Any thoughts? Thanks in advance.

Well lesson learned, I need to not stay up so late working on pins. I looked at that switch last night even squeezed it together while it was in the endless scoring loop and it didn't do anything. Revised this morning per your suggestion, cleaned it with alcohol and now it works. That was the culprit. Thank you.