alternators

[rod donner]

Help
I have a 1973 Press. 337 that when descending from alt.{airspeed a little higher{} the front alternator out light comes on. However when I turn off the rear alt. the light for the front goes off. conclussion; even now when I am in level flight the front alt. out light comes on intermittenly, if I shut of the rear alt. the light for the fromt alt. goes out, or if I load up the elect. system, for example turn on all elect. including landing lights,then front and rear light stays off. this is a two regulator system, I checked the front alt. by trying to turn it using cooling fan, cant do it . any ideas, thanks ;
thanks for the clue on the gas gauge, there was corrosion in the plug at the wing root. this is an awesome information center.
Rod Donner