I'm working on a Six Million Dollar Man for someone in my town and have made a little progress but seek some help.
He bought it DOA. He then bought a new MPU that came out of a working Super Sonic, with Super Sonic ROMs/Eproms.

I tested all test points on the PS board and everything checked out fine. I put in the new MPU, not knowing it had SS chips on it, and the game booted partially, got the 7 flashes on the MPU LED, but that's just about it. No start-up tune, and only goes through the lights and display test....no solenoid test or sound test.

I realized later that it was a SS board, and I stole the chips from the original MPU and swapped them with the SS chips. I did this for the chips in the following locations: U1, U2, U6, and U7.

Now it boots up, can accept a coin, and displays "000000" as a score, but will not start a game. In test, it does the same as before- lights flash, displays work, but no solenoid or sounds.

Any ideas? My time with the machine is limited since it's at someone else's place (actually a business).

There was no changed when unplugging the sound board nor when holding in the flipper buttons.