I then went to the next step Shut off power and installed #5AR4 Rectifier tube and two KT-88 output tubes on left side only, when I attempt to adjust bias on the front left output tube it raises in value initially but then gradually reduces back to about 1.9 volts no matter were I adjust the pot, I tried turning the pot up all the way (cw) to see if that would stabilize the bias and noticed the tube started to emit a lot of heat and noticed the tube was starting to get much brighter/glowing so I shut off and checked the wiring but found no issues.
I'm not sure what to do at this point.
Any help would be greatly appreciated.