OP

Quoted from drsfmd:

My Gold Rush has suddenly stopped working, and I'm a little stumped as to why.
What's happening: Game is set to free play via a rewiring of the coin return button to be a start button (I've never seen another one does this way, but it's worked for the 45+ years that the machine has been in my family). When I push the start button, it initiates startup sequence, and will reset the score reels, then stop and turn off. A video is below.
» YouTube video
If the score reels are zeroed, and I push the start button again, it will sometimes add score to the ones or tens reel, and if I push the start button again, it will zero those reels out. A video is below.
» YouTube video
I have a schematic (there's no manual available for this machine), but I can't figure out why it the machine would shut off like this. I found this thread (https://pinside.com/pinball/forum/topic/bally-1964-startup-sequence#post-1350163) that discussed the startup sequence of a 1964 Bally machine-- can I assume that this applies to my machine as well? If so, it makes it up to at least "The reset relay, through the score motor, will reset the stepper units (zero the ball count and player units)." I can't say for sure if the next step ("The coin relay, through the score motor, will decrement the credit unit.") applies or not, as it's a single player, "add-a-ball" version that doesn't record more than 1 credit (but the add-a-ball stepper does decrement).
Stumped... any guesses would be welcome.