804B fermont drops voltage under load

Hello,
My 804B drops voltage when a load is applied. No increase in RPM is audible.

Notable:
1. % current guage always reads 0
2. % power guage always reads 0
3. Am/vm guage only reads voltage in
position L3. All other positions show 0
even though voltage exists.
4. when the hz are increased, the voltage
and RPM increase.
5. No low voltage fault lite appears.

Questions:
1. How do you know if the exciter is
functioning?
2. How do you determine if the voltage regulator is functioning?

Thanks
Gary