So when I finally got the opportunity to really crank it (wife out of house), the "normal" channel of my new 5E3 worked just fine. But when I plugged into No. 1, bright channel and cranked it up, loud squeal. Subsequently, on playing around with it, I also was getting a tremolo like sound--start, stop, start, stop. I've re-flowed the solder on the connections at the jacks and all appears to be okay. Also re-flowed the solder at the grid stoppers. I'm getting good 1M resistance on a 1/4" plug in the Bright jack. I've also replaced the 12AY7 in V1 and same result. Upon playing with it a little more, I noticed the squeal and tremolo effect goes away when the tone pot is at zero. Could a bad tone pot be causing my problem? Any other thoughts?