Quoted from ivanx:
The red circled switch continuity tests as *always closed* regardless of the state of the game. I've pulled the jones plugs from the backbox and the switch tested good manually after that so i know the problem isn't in the backbox. What switch is this in the schematic?
I think the switch you circled is the Ball Count Zero Break switch. When the Ball Count unit reaches zero, this switch should open (or break).
It's in parallel with a normally closed switch so it will read closed unless the 2nd Coin relay is held in the active position. I don't think this is your problem.