Did you test connectivity from rectifier pins to the other boards?

At test point 5 on the solenoid driver board, do you have approx +12 volts DC? If not, then problem is between the SDB and the rectifier board.

If yes, then measure for +5 volts at test point 1 on solenoid driver board. No +5 there? Then the LM323K regulator is bad.

Connector problems.

The +12v input and return wire.

Check for 12v on the driver board and a solid common return at the negative terminal of the c23 filter cap. Bally isolated the 12v ground return wire and it is common place to find a burned up connector. The 12v ground return is an orange wire. You can check for +12v at the positive terminal of the same cap. The driver board turns 12v into 5v with the LM323k

Return is ground. The 12v ground return is isolated in a wire back to the transformer board instead of being common to the other grounds right at the driver board. This ground return wire is what goes bad most often to cause your symptom.

Meter set to VDC. Black lead on C23 negative, red lead on C23 positive. It should read over +12vdc. If it does not, check for the 12v on the rectifier board. If you have +12v on the rectifier board. Connector problems likely at the 25pin connector on driver board.

"Connectors,Connectors,Connectors!" That's the first thing a good friend of mine tells me to check on the older Bally and Stern games of that era. Glad you found the culprit.

consider tying c23 negative lead to the common ground on the driver board. That reduces the stress on the orange return wire that likes to burn up on driver j3