Thanks for those pages! I have added them to my stash of documentation that I'm accumulating.
So I rigged up the fuel tank so that I can run the engine and have access to the regulator at the same time.
I checked the wiring between the alternator and regulator in particular the F and N terminals. They both check good. I also verified that both relay coils on the regulator are good (applied 12V), they are.
As soon as the engine starts, one of the relays is energized and the charge lamp turns off. The coil on this relay is the one wired in series with the small resistor. So I know that is good.
The other relay is never energized, which keeps the circuit energized that feeds the field and keeps the alternator charging the battery with excess voltage.
I found this general description of how the interaction between an automotive alternator and regulator:
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The voltage regulator controls the field current applied to the spinning rotor inside the alternator. When there is no current applied to the field, there is no voltage produced from the alternator. When voltage drops below 13.5 volts, the regulator will apply current to the field and the alternator will start charging. When the voltage exceeds 14.5 volts, the regulator will stop supplying voltage to the field and the alternator will stop charging. This is how voltage output from the alternator is regulated. Amperage or current is regulated by the state of charge of the battery. When the battery is weak, the electromotive force (voltage) is not strong enough to hold back the current from the alternator trying to recharge the battery. As the battery reaches a state of full charge, the electromotive force becomes strong enough to oppose the current flow from the alternator, the amperage output from the alternator will drop to close to zero, while the voltage will remain at 13.5 to 14.5.
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Not sure what else to check at this point...