The start relay in the 4104 has a history of sticking from long term point degradation. It causes the starter to keep cranking after releasing start button. Will burn up starter if you can't disconnect batteries quick enough. I believe the culprit relay is in the voltage regulator box. Common Little relay. Should be replaced if owner hasn't already done so.
For whatever its worth the instructions that came my Delco were very specific about having a second start relay in the circuit. Power from the key energized that start relay and it energized the start relay on the starter which in turn energized the solenoid on the Delco. It seemed like overkill to me but that's what the instructions said.
Update.