[TenTec] Hercules II power output (low?)

[jon_kanter@charter.net]

Hi All,
I recently purchased an old Hercules II power amp. I'm running it on a marine deep cycle battery that I got at Walmart (115AmpHour- biggest one they had), with a 15amp charger.
The problem is that the amp doesn't appear to produce rated power on all bands. In fact, driving it with a 100W transmitter, I can only get the rated 500W output on 10m. On 40m and 20m I can only get about 300W out. This is either into a dummy load or the antenna tuner.

The schematic shows pots for bias adjustment, but no indication of what it should be.  

I called Ten-Tec, but they just recommended to send it in for service. I thought I'd first see if anybody on this list had some knowledge about this they were willing to pass along. Does anyone out there have experience that might be of help?

Appreciate any assistance you can provide.
Thanks!
73,
Jon AF1M