ECN Forum Forums General Topics of the Trade General Discussion Area Hertz problem on 3ph gen

This is a Kohler 6500W generotor 3 ph 208/120 output auto start NG. Very old model.
The voltage is good at 122V
The hertz were very high.

No load test
(leg A to C) hertz high
(leg A to B) hertz 50 to 90 all over the place
(leg C to B) hertz 50 to 90 all over the place
(All legs to neutral) all over the place
I then connected a load of 15 amps
1 three phase motor 3HP
and 3 resistive heaters (electric stove large burners)
Adjusted the speed of the motor to 58-60 hertz from leg to leg voltage is good.
That B leg still has fluxuation.
All legs to neutral have fluxuation.
All voltages are good 208/120
Generator is 208 delta with transformer in gen panel for 208/120Y

Does anyone have a idea for a fix on the hertz