Hi all! Quick story: I bought a used WT800C about three weeks ago; the serial number dates it from 2008. Tested it out, sounded great, and bought it. Since then, the sound quality has suddenly deteriorated. When I took and home and played it that day, I set up the amp properly as instructed by the book, turning down the master, turning off compression, and setting the gain based on the "set limit" light. It played beautifully, set at 12 o'clock. Now, if I turn the gain anywhere past 9 o'clock, I get what I think is distortion -- it sounds like ppppbbbbbbbbbttttttttt. (Can you tell I'm new at this? ) If I set it up properly again, 12 o'clock (where the light blinks, still) it's unplayable -- it sounds terrible. At 9 o'clock, it's really really quiet, even if I turn the master way up. Any ideas on what's up? I tried a new tube. I couldn't find a Ruby 12AX7 in town, but found an Electro Harmonix 12AX7 and swapped them, but no luck. I tried a different bass (an active Ibanez bass), no luck; different cabinet, no luck; different channel, no luck. Same with different cables. I'm rather disappointed at present.