Channel 2 Mark 1 mode

I recently purchased a Mark V head. It’s my second one. Still don’t know why I sold my first!! Anyway, when Set to channel 2 - Mark 1 mode (normal or bold) I get a horrible equal when I try to set the Treble or Gain to anything past 3:00. Whether EQ is on or off, any wattage setting... No other issues with any channel, setting or feature no matter how dialed in. Any thoughts? Could it be a tube or best to have a tech diagnose?? Any advice or opinions welcome. Thanks.

The V2 tube only affects channel 2 so I’d start there for sure....perhaps those settings are just pushing a tired tube over the edge

Definitey start by replacing any tubes related to channel 2 as mentioned. It sounds like a microphonic tube could be the culprit. You can check this first by taking the cage and tube cans off and lightly tapping on each tube with a wooden or plastic pencil. If you hear the squeal start, you have found the tube which needs replaced. Mesa has a video about this somewhere.

Thanks! I have a spare tube so I will check the tubes and see what u find. Will start with the tube in the V2 location!