Too much current going through that "red glowing" tube! Shut the amp off immediately! Not enough bias voltage on that tube! Does each output tube have its own bias adjustment pot? When replacing s tube set these will have to be checked and adjusted for current draw. One of the joys of owning tube amps. You will need a multimeter and probes. And an insulated screwdriver! A circuit diagram would be handy, too!
MC275 Gordon gow
Hello I’m running two Mc 275 Gordon gow. I installed brand new kt 88 gold lions in both amps my first one the tops of tubes glow . The other one the whole tube are burning orange. Is this normal thanks scooter