Grinnin... your posts make sense now that I see the rotor, as you said, the field induces the rotor and the rotor induces the stator. I've seen a lot of generators, but not quite like that.
you should be able to put battery power on the field coil with jumpers to bypass the regulator and give you an unregulated output. one field lead to battery plus the other to minus. even the polarity won't matter
points style regulators typically give full field through the closed points. the resistor is in parallel with the points and when system voltage is reached, the points open which puts the resister in series with the field. this will reduce the field's strength.
another way to check the rectifier and the stator is to use a clamp on amp meter if you have one. put the clamp on to the output to the battery (from the rectifier) and set it on AC. run the engine and turn on everything electrical. bad parts will give pulsing DC that the meter reads as AC. There normally is a slight pulsing DC on top of the rectified output but any reading over about 1/2 amp AC is bad.
if you have an Oscope...
bad stator coil: