I have a nice and dirty Fisher 500b was found in an attic.Its missing one output tube and no case or feet and no AC plug (it was in a homemade cab ) . From what I can see its complete and all the tubes are Fisher with one output tube being a Westinghouse .I'm on fact finding mission before I start working on it. I found a few threads and have the SM. What I could use is the Replacement PN# for the selenium rectifier . I noticed there are some resistors mod also. Any info or suggestion would be greatly appreciated . I'm not a tech but can do the work . Thanks