I got an as-new B-50R at a pawnshop last weekend - shiny tolex, plastic still on the control panel, hangtag, great sound! I finally found my practice amp. The one thing I didn't check was the volume at extremely low settings. I have no sound from the amp with the volume set from 0-1; when I get to 1, a little crackle occurs and bass kicks in. Is this simply a matter of a dirty pot, or something more serious? I need the low volume to be able to practice after the kids go to bed. Thanks for any advice you can give me.