yup, first step is always verify where the issue is, because military gauges are mostly there just to give you an idea of what it's doing, and you only worry when it's different than you are used to.
The TMs for this unit are all here:
This should be all the TM's and additional information you need to work on the MEP-803A
www.steelsoldiers.com
If the gauge is correct but voltage is low, I would look at the voltage regulator itself as being a possible issue.
Someone else can chime in if I am wrong, but in all of my working with generators I've never come across one that the voltage output was at about 80% of rated output where it was a failed gen head. Also very unlikely it's a bad wire connection, though I suppose that is possible as well.
Looking around, somewhere I read that there is also a voltage adjustment potentiometer inside the voltage regulator as well as the one on the control panel, and in one case that was the issue, fixed by using a little Deoxit in that potentiometer, letting it soak, and working it for a bit.
That was this thread:
Yesterday I started up my 803A just to circulate some oil and I noticed that the voltage was reading 220v and I had just ran it a month ago and it was set at 240v. I attempted to adjust the knob and could only get it to 230v before hitting the limit of the knob. After a few attemps at adjusting...
www.steelsoldiers.com
If it comes down to replacing the voltage regulator (or you just want a spare on hand) in the classifieds section there are some replacement regulator setups being sold by kloppk.
MEP-802A & MEP-803A Voltage Regulators Replaces TRC 19580 88-21063 6110-01-363-0492 Features include: · Replacement for your defective or missing Voltage Regulator... or to have a spare on hand · Works in generators that have defective Quad Windings! · Supports the 802/803's Field Flashing...
www.steelsoldiers.com