Looking for wiring info on D364 Generator Set

Was working on an old D364 generator set this weekend S/n 21B249. Got the engine running for the first time in who knows how long and she runs great. Next question is getting it to make power. The last set I worked on was a D4400 and turning the exciter commutator down in the lathe did wonders for it and it now works great. I am far from an expert with generators but I will share what I think I have figured out so far.

This set is arrangement 2H4815 as gathered from a service manual that shows pictures of what looks to be the exact same set. The electric panel has a tag stating it was made by Eseco (Electric Service Engineering Company) and is a type 4200K s/n 7974 I believe. The generator is a Marathon Electric model 586ACD76. A quick google shows they are still in business so I think a call to them might be worth something.

Anyway the D364 will make only 7 volts which can be traced to the exciter making only 5 volts. I am not sure where to go next as I cleaned the commutator but it seems out of round and I am not sure if the brushes can keep up with how out of wack it is. I am not sure how this exciter comes apart of how it is removed from the generator. The other problem is the rheostat which controls the field voltage is very dirty and rusty from age. I think is were terminals 4 and 5 in the top right Bus Bar in the picture of the panel that are the wires at the exciter. One is a dead short from the exciter to the connection and the other had 58 ohms resistance so I think it may run through the generator before the panel. There is a third wire with the two that i know are coming from the exciter and I am unsure of what it is unless it has to do with the automatic voltage regulation or something. Even though there is a switch to change between manual voltage regulation and automatic voltage regulation the one wire from the exciter seems to be hard wired to the rheostat which I would think would be for manual operation only.

Any help will be appreciated.

Sam