"fisherdoctor.com" I think, will sell you a rebuild kit, with intructions that you could then give to just about any qualified technician in your area. Try googling fisherdoctor and see what comes up. Then try googling "electronic repair columbus ohio" and see what comes up. I hope this helps you.
Fisher tube receiver rebuild, Who can provide help
I have purchased a fisher 500B receiver, it is working good, I have replaced the 4 7591 output tubes, the old ones were fisher tubes, original,but somewhat closed in sound, insatlled 4 new electro harmenex 7591a'seh.now I would like to have the rest of the receiver rebuilt, I am told the output caps should be replaced, I live in Columus Ohio, so someone near here would nice, anyone know who could do the work, who has experience with this receiver, and would do good work, please only respond if you have had work done by this person, thanks Alan.