Hrmm, strange, I always run the generator at 60Hz from start up as you recommend on your site, so I do not think that would be the cause. Are there any other common causes of the voltage regulator panel breaking?
I think I found the issue. I opened up the control box and took a look at the voltage regulator on the left side and found that component C11, line 17 of the voltage regulator board was fried and had bubbled out the side of it. In Figure 6-4 of this manual,
you can see that in the DC voltage test, this component is part of the circuit that you test.