RA 100 problems

It's not as loud as it should be. When I turn the treble down the amp gets louder. When I turn it up it sounds like crap. I changed a power tube that was burning hotter than the rest. It sounds better but still isn't right. Any suggestions?

I'd call Mesa. They'll tell you exactly what to do.

What channel is affected? Clean uses only V4 and V5, Hi/lo uses V1 and V2. It may be associated with a preamp tube.
V3 is the Effects loop tube, V6 is the reverb and V7 is the PI. If your issue is associated with clean or Hi/Lo it would be related to one pair of preamp tubes. If it effects both clean and Hi/Lo I would assume it is V3 (check V3 it should be a 12AT7). It could be the PI tube as well if half of the PI tube is failing to maintain balance or is due to be replaced. If you had one of the power tubes running hot and the other not, it could be the cold tube that is not operating properly. I had a similar issue with one tube that was turning off (if there is current flow in the tube you would see the blue glow on the cathode, if it is just yellow or red but no blue hue it may be off which will cause its counter part in the pair to run hotter. Either a bad tube, poor socket connection, or screen resistor issue.)