I know there have been some earlier posts but didn't find them in my initial search. I have a Rivera Pubster 25 that's developed this odd grainy distortion and lost about 30% power. This despite changes in preamp and output tubes, different speaker, etc. Anyway, I know there are some decent techs in town, but wondering if anyone has used someone in the western suburbs (Valley Forge-West Chester area) that might be able to help. Thanks!