Trem-o-verb Red Channel cuts in and out (drops gain) sounds

I have a trem-o-verb head. I have a issue where the red channel (blues/Modern HiGain) will cut in and out, drops the distortion and volume drops. It will do this right away (no warm up) and randomly. The gain doesn't sound tight and sounds kind of fizzy.

Power tubes are MESA and check out all OK and matched. The preamp tubes are all NOS tubes. I had this problem before changing the preamp tubes but only on the BLUES setting.

I would appreciate any guidance and help with this issue. I bought this amp used. THANKS

Probably an LDR (channel-switching component) - this is a very common problem with the Tremoverb. If the gain drops, it will be one very early in the circuit, probably LDR1 or LDR8. Changing them is a job for a tech, or back to Mesa for a full overhaul if you're in North America - they will change all of them, there are 25 in the amp.

Any problem with the amp that affects only one channel or mode cannot be a tube problem because all tubes are in use all the time (except for the FX loop tube if you have the loop assigned to one channel only). If something seemed to affect only Blues and not Modern, it's most likely either a different LDR, something else in the switching matrix, or a weird coincidence... mine did the same thing at one point and it seemed to be only Blues that was affected, but it was a coincidence and it was actually LDR8 that was faulty.

I had a similar issue with my rectoverb. My Red channel would completely drop in gain and volume "randomly while playing. Turned out to be just bad tubes I thought were good in V3 and V4.

look here about the "Cathode Follower" http://forum.grailtone.com/viewtopic.php?f=4&t=25102

Also, make sure all your connections are good from guitar to amp. If you have any pedals or fx in your chain, eliminate them for now.

Check your footswitch connection at both and and make sure they are secure.

The Rectoverb is different because it has two separate signal paths for the channels, so a problem with V3 only affects the lead channel. In the Tremoverb, all the tubes are used on both channels, it's just the control networks that are switched.