There's been a discussion over on Gretsch Talk. A member solved his Princeton Reverb rattle issue... it was the ceramic tube sockets! I just thought I'd pass it along. I know some people have fought this for a long time. The metal retainers don't fit the notches in the ceramic. He replaced his and .........Gone! "For me it happened when I would hit the low A. It was a sustained rattle and it was very easy to hear in the studio while the amp was miked up. I didn't know if the cabinet, or the speaker or a plate in the tube was rattling. I finally took the back panel off and while playing the A note I reached around with my polishing rag and grabbed one of the 6V6 tubes - the rattle instantly went away. I put the amp up on the work bench and found the defect in the tube socket that is plain to see in the photo. Vibration from the speaker caused the tube socket to rattle. It didn't happen when I plugged the amp into another speaker cabinet so I knew right then that it was a mechanical noise not electrical. Damn I am so happy that it's gone. The new Fender amps are very capable of sounding good if you are willing to work out the bugs. I could see this being a problem for someone who's unable to trouble shoot this stuff. Chances are they get fed up and return the amp and I don't blame them at all."