Bought another black hole today, that I can’t figure out how to get off free play.

Previous owner had installed a double stack switch behind the start button.. one switch for start and another one stacked for coin, that tapped into the right coin mech. I replaced it with an original single switch for the start button circuit only.

When hitting the start button with nothing on the credits display it still starts as many games as you want for free.

When I trigger any of the credit switches, it makes a credit sound but never puts a credit on the apron display.

The apron credit display works, I can add service credits and the display will light and increment credits with each service button press.

The diode board jumper is not present, and the roms appear to be originals.

Any other ideas how to get this game off free play?

Turns out the legacy stacked switch just piled up a bunch of credits.

The credit display was off (switch 28 on the MPU). Once this was on I could see 24 credits were still on the game making it look like freeplay.

Service credits must be a separate cpu construct..