OK, I checked the hopper limit and it was set at 50. When the machine is off the diverter solenoid in de-energized. With the machine on but power removed from the solenoid the coin drops into the hopper. With the machine powered on the solenoid immediately energizes which diverts the coin to the overflow. Something must be telling the solenoid to energize all the time. Not sure if the energize the solenoid signal is from the coin comparator, coin hopper, or the MPU sending a divert signal because of a setting or other problem within the slot. I could just leave one of the power wires disconnected from the diverter solenoid but I would rather continue to investigate the issue.