Today's issue is with the Solenoid Expander board. I think I might have a bad relay, but I'd like to double check.
In attract mode with the 10-pin connector attached, pins 7 and 9 show 44VDC, and pin 5 shows 58VDC.
Power down, remove connector, power up and test voltage at connector pins. Pin 5 now shows 7VDC, pin 7 shows minus millivolts, and pin 9 shows 44VDC.
The SEB relay does give a single click at power up on the 5th flash along with the relay on the SDB. The SEB light under the playfield never comes on.