Started with thinking there might be some strange voltage leak through J6. Voltages at the playfield motor seemed to check out ok and not associated with J6.
Randy provided an excellent checklist and systematically went through the machine.
Thought it might be a grounding issue. Traced ground wiring all over the place. The connector on the power board, J14, that was supposed to provide the motor ground wasn't. The schematic shows 2 wires at J14, I had only one. Seemed it may finally have been some how connecting with ground on the EL board by some other path. Haven't actually found the ground wire path there yet.... but
After plugging and unplugging connectors for a couple days it magically all worked when put back together. I'm assuming a grounding issue somewhere got solved by reconnecting one of the plugs.