MC275 Gordon gow

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 

Mcintosh. Google it. They will refer you to an authorised dealer, closest to you. north or south pole. :-)

No there is no adjustment, for the bias. It is fixed.

AGAIN, that 12AX7 or 12AZ7 in the right front corner, can cause a problem...

Did it do it before the valve swap? If not THINK?

Why would it need to go to the shop AFTER a power valve change?

What did you do, or it do... OR is there anything wrong to begin with..

You have two of these things, I own one.. of the GG models and one of the older 62 models.

Red plating will burn the new valves right up.. If there isn’t a problem with the valves to begin with. There will be soon..

Get the Old valves and check it out.. FIRST don’t keep playing it...

Your not bi amping and one is bass duty, is it?
That could get the plates a little brighter, I suppose, not much though..I don't know, have to think on it..

Regards

Thanks for all the response! I found a Mac service center about 40 mins from my home taking both in for check up and repair if needed.