Quoted from Pintime74:
I am checking the playfield switches now. Prior to manually setting the score reels to zero, the score motor unit would run continuously. I unplugged the plugs for the door and playfield and the score motor unit would continue to run. When I unplugged the plugs for the backbox the score motor unit would turn for a second and then stop. With this I has assumed it must be in the backbox. Would it still be in the playfield if the score motor unit continues to run with the plugs for the playfield disconnected?
Two different problems. The score reels not resetting to zero, causes your score motor to run non-stop. Manually setting them to zero, stops the score motor, completing the reset. After that, something is causing the relay in the backbox to stay on. If it is a "Points" relay, you probably have a switch closed on the playfield. Or the hold switch on the relay itself may be closed. You'll have to figure out what specific relay is stuck on. It will be warmer than the others.
The reason why the score motor continued to run with the playfield unplugged was probably because it was still trying to reset the score reels to zero. Try manually resetting the score reels to zero and then try it again with the playfield unplugged.