Kohler 7.5C62 voltage falls off while running

[Dtarsi]

Generator starts well and runs about 15 minutes on 1/2 load. Then the voltage goes to zero, dumping the load. Generator remains running. After a short time the voltage comes back and load is re-established. Again it goes thru the voltage drop scenario. Before this happened the generator seemed to slightly hunt at load and I could see a slight varying of voltage and frequency. Found from Kohler that the price of a new regulator kit was around $500. Don't make the original type. They also, said that Kohler no longer supports the alternator and the voltage regulator gets an AC input from the stator. Has anyone experienced this problem? Is it probable that this is a regulator problem or heaven help me, a stator problem? Thank you.