Hi, I've had this issue before, and it usually solves itself, but it's sticking this time.

I own a used Flextone II XL (2x50)

i've had it for 4 months now, and it's worked like a charm

every now and then though, i have this issue: the amp will be at a 5 or a 6, but sound as if it's less than 1. You can hear it, but it's quiter than a bedroom amp on 1 and there is this hissing noise as well

Usually it happens right before band practice, and then it solves itself in about 5min or so

but i've been at it for a half hour and i've gotten nothing. i even let it sit and went back to it and that didn't work
idk what to do. And any and all varible you could think of i've tried (even though i know it's the amp because even when nothing's plugged in i still get the same hissing sound)

• different outlets
• unplugging sound board
• not going out of wah pedal
• different chords
• different guitars
• ground/lift switch
• live/studio switch
• channel switch
• bank switch
• turning it on and off

HELP! I NEED IT!