My new tube amp - Fender Super-Sonic 22 V-Custom Limited

  I purchased a new tube amp on e-bay,  a Fender Super-Sonic 22 V-Custom limited. It has custom gold color tolex with black tolex (with white piping) in a v-pattern on the top panel. It also has a Celestion Vintage 30 (12") speaker, and black grille cloth. Only 150 were made, so I think it is special. It was delivered to me in its original packaging, and I couldn't wait to to try it out. So, I turned it on and it sounds great at all settings, except I had a problem with the reverb - it squealed with feedback at settings higher that 3-4 on the reverb knob. It was not feedback from the guitar, since it fed back with nothing plugged in - just by turning up the knob, then excessive squeal. Since it was brand new, I felt like sending it back, but since it was so special, I didn't feel like sending it back either. So, I sent an email to the company I purchased it from, and asked what to do. In the meantime, I couldn't wait to figure this out, because it seemed rather minor to me, because with the amount of reverb I use it is  below the feedback point, and I really did not want to send it back. I thought to myself, I still could use this amp - even with this minor flaw. But, being the engineer that I am, I decided to fix it, and I started out by doing a web search for everything under Fender Supersonic 22 reverb feedback. All the suggestions led me to tapping on the tubes, which didn't lead to any reason why I should change a tube, but then taking me down the path of removing the reverb tank and bag. After just looking inside, and trying to touch anything I noticed a grommet out of place, causing the reverb spring assembly to be in contact with the reverb tank enclosure. It also limited movement of the reverb spring assembly and probably less reverb, that I didn't notice due to the squeal. After I partially re-assembled everything, the squeal was gone (at first). After I added the screws to hold down the bag and reverb tank, there was still some squeal with the reverb knob above 7. My next step was to try to isolate the problem, and my guess was that by tightening the screws, the reverb tank was getting some resonant frequency from the cabinet. I decided to try to isolate the tank mounting from the cabinet, and I then added a small piece of foam under the reverb bag, and I also added plastic spacer in between the bag and cabinet, held in by the screws. This worked with the screws loose, but when I tightened the screws too tight, and turning the reverb knob, the squeal cam back, so I loosened the screws just enough to hold the tank in place, but not allow feedback squeal to occur. After I did some more web searching, it turns out that is sometimes a common problem with spring reverbs mounted to the cabinet. So much, for new discovery. But now I can keep my special amp and know that it is even more special to me.