MA2275 Issue need some advice

I should clarify. Section B of V4 and V5 tubes are for the left channel. Section A of V4 and V5 are for the right channel in these phono tubes.

Section A of V6 and V7, tubes is for the left channel. Section B of V6 and V7, is for the right channel of these gain tubes.

Hifihvn, again thank you! So given what you have found out what do you think is the next step? Should the tubes be replaced? Something else? Thank you!

It would seem odd for two tubes to have a bad side. Those two phono tubes are like a spare pair of used tubes, when using them in the other inputs like CD. It still might be worth trying a couple of new 12AX7s. All the other tubes should change the distortion over to the other channel when you switched them, one would think. Did you swap the CD left and right outputs to the amp to make sure the CD player left channel doesn't have the distortion? Or, use another source, like a spare CD player, DVD player, etc. If you did and no changes, I'm thinking repair time. Don't hold me to this though. Anything is possible...

Are you positive it is the Mac? Have you swapped ICs left to right at the source only? Or try another set of interconnects from source to amp. You may be looking at the wrong component for trouble. Good luck.

There are fuses on the power tube board sections of both left and right channels if one of these fuses blows you may get noise like you describe and also low volume output from the channel with the blown fuse. It then may be that a new fuse will correct the problem or there may be a bad resistor or other part on the circuit board. Don't know if this is the problem with your amp but is another possibility.