God dammit punch a child in the face.
So I got my 8100 back from the shop today, and the volume issue is fixed, it's loud, it's raw, and its metal.
But the damn 'treble shriek' persists. I call this, because the problem is relegated to the boost channels, and it only happens when I take the gain above halfway or the treble above 4.
Has anyone else had a similar problem? I know it's not the tube, and everything seems to be fixed. The note said the tech had to repair an auto transformer, he couldn't get a replacement. Maybe this is where the problem is. I'm including a link to the schematics for the amp, so if anyone here knows what's up, please help.
New development. The problem goes away if I turn the boost channel down. it also varies where the problem starts if I mess with gain and treble.