WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
This is probably a ballast resistor for a series heater string. Such amplifiers are potentially very hazardous unless an isolation transformer is used.
I added an isolation transformer in line, I would like to test that resistor but i cant find any info on it,or another one.Its been getting hotter and hotter lately.