I see what looks like a wiring hazard, with the yellow wire looking as if the bare part could touch one end of the soldered-in fuse. This would be a bad idea.
In the shadow under your finger there should be a filter capacitor tucked under the tie strip lugs. Its positive end will be soldered to a ground lug, and the negative end to the lug where the diode's UNbanded end is soldered. If that capacitor fails, the bias voltage will fall basically in half, more or less. None of the electrolytic caps we can see in the pic appear to have been upgraded since this unit was built 40-plus years ago. That kind of component is not meant to last even half that long. Sometimes they do, and break down in a more-exciting way after you put them back into service after years of sitting on a shelf. Changing them all, or "re-capping" as they call it is the only sensible strategy if you want to use the amplifier.
Your description of the relay problem hinges on one clue. When you unkey the mike and lose your receive, does the relay go "click" when released? Or does it just stay silently keyed up after you unkey the radio?
If you hear it go "click" every time you release the mike, cleaning the contact points with a paper strip soaked in solvent may fix the fault. And if the relay is staying activated, and won't go "click" when you release the mike you could try changing the 6AQ5 tube to see if that makes the relay release properly.
73
I agree that I need to recap the entire unit ! Also is the cap that you are referring to the large 100 mfd 150 VDC cap under the fuse there in the photo ? Thanks 
