MC275 Gordon gow

Haya, They don't look the same? They call it red plating. Makes no difference. Put the old valve back in and check, be aware, signal valves can cause problems too with the power valves..There is a 12ax7 in the left front corner of the signal cluster.. Make sure that valve is in good order.. It can cause a problem when using the RCA input, If I remember.

Why did you replace the valves? Was there a problem before?
Did something quit working? Did you get a chance to listen to it?
OR did you just shut it down?

Regards..

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!

It runs and sounds great .who repairs these units thanks