BURN RESISTOR GRID IN INPUT TUBE !!
Why could it be?
Perhaps an improper DC offset in the driving device.
As Baudouin0 says please either provide a schematic or what is the make/model of your amplifier ?
If this is the first stage then as Eli says --is there a DC component being inputted from your--CD/turntable - preamp- etc ?
Rarely I have found an internal short circuit in the elements of the tube --without some more information all this is supposition.
If this is the first stage then as Eli says --is there a DC component being inputted from your--CD/turntable - preamp- etc ?
Rarely I have found an internal short circuit in the elements of the tube --without some more information all this is supposition.