I'm using a B-52-LG-100A 100-Watt Solid-State Amplifier. Recently the master volume control doesnt seem to be adjusting the volume. It's like the volume is stuck on level 1. I can hear the guitar playing but its so low I have to be within a few feet of the speakers to hear it.  When I turn the master volume to 10 it doesnt get louder and when I turn it all the way to 0 it still stays the same. I've taken the whole thing apart and checked for any visible damage inside and everything looks perfect. I've tried different power outlets, power cables, guitar cables, etc., but nothing seems to help. Does anyone have any idea what could be wrong with this?