Mep004a no power after startup

[polarbear119]

I've got an Mep004a that I've previously converted to single phase. This set has ran fine for the first few years after the conversion. This issue started as intermittent but has now went to full blown dead. I've bench tested pretty much everything in this set and have found no issues. I'm hoping someone can point me in a direction to get this thing going. It's getting harder to explain to the misses why I keep buying parts and get the same results as I did prior to touching it. Here's what I have so far. My symptoms are I hold the start switch up for a few seconds after it fires. I have about 100 volts ac and 3.0-3.4 volts DC on F1 and F2. I let go of the switch and I lose the volts I did have. So far I have replaced almost all the parts on the VR board. The board now bench tests better than before and is almost dead on spec wise. For the exciter half of the box, I've replaced C2 and the 6 scr's. I have also ran the bench tests on the entire assembly with all tests meeting specs. All components look good, no burns or corrosion. I have also rebuilt the DC Relay assy in the special relay assy. This card also bench tests ok before and after replacing the resistors on the card. The resistors on the DC relay card where burnt pretty bad but they still bench tested good. I replaced them anyhow. I also replaced R31 & R35 while I was in there. I have also verified the micro switches in the speed switch. I have also unplugged the speed switch and jumpered A and C. I then flipped the start switch to the start position. With the field wires unhooked I get 24 volts through the VR/Exciter box and to the jumper block. This same test with the field wires connected yields me 3.0-3.2 volts DC. Am I missing something here or failed to test a part yet? After rebuilding the VR/Exciter I did have a couple test runs where I had real nice 120 volts and running good. It was intermittent at first but now I'm not able to get it to hold voltage no matter how many times I fire it up and test it.