Have you ever seen this gen set work right?
Is it new to you, or have you had it a while.
Do you have all the TM's downloaded from the Forum, so we can try and help you?
I have a 1992 Libby MEP002a. The gauges appear to not work, none of them. The engine runs fine without issues. The only issue I have so far is the voltage adjust does not work. (By not work, do you mean, it produces no A.C. Voltage? Or do you mean it reads "something" and that will not adjust?) I have a Kill-a-watt meter that I used to measure the output. I can get the HZ close by adjusting the idle (There is no idle on this set. Try very hard to never run the set at low RPM. Its not good for the A.C. volt regulator. Also know, that if there is no A.C. voltage being produced, the Hertz meter can not work.) however the voltage adjust knob, which I assume is for fine adjustment, does not change anything. What part do I need to replace or where do I need to start looking. I am not a mechanic so dumb it down for me.
Keep in mind. If you do not hold the S1, (start switch) in the start position long enough, the gen set will not produce A.C. voltage. If you have not read the start procedure in the -12 TM, please do so. Also, make sure the S& and S8 switches are properly set for the output you want. Instructions for that are also in the -12 TM.
Start the set. measure at the output terminals, after turning on CB-1, (A.C. Output CB) to see what if anything is being produced.