OK all, it's been awhile since I've played my 68 DR (ie, a few months) and I was playing it today with a few pedals and my SG, and it started making a high-pitch, feedback noise that sounded like it was coming from either the speaker or tubes or something. I thought maybe it was the pedals, so I ran the cord straight from the SG to the amp, and it's definitely the amp. It will make that noise even if I have the volume turned down to 0. I turned the standby on and let it sit for a few mins, then turned it off, and the noise seemed to disappear, but then it changed to a sort of static sound, like you get on a cordless phone. The amp is in my playroom, and the floor is carpeted and there's a TV but its not right next to the amp. The noise seems to go away for awhile when I tap on the amp or even turn some of the knobs and teh end of the guitar cord at the input. Weird. Anyway, any idea what the awful noise could be and how I can get rid of it? It was doing a similar thing a little over a year ago and it needed a new reverb tube, but it's been fine ever since. I've tried to do a video that will let you hear the exact high pitch noise it's making. I will upload it shortly.