I just snagged an old Sunn 1-18 cab from a Craigslist ad. The previous owner had done some strange things to try and stop the rear panel from vibrating, so after some weatherstriping tape and decent screws, I've solved that problem. But... Long story short: It has an 18" Jbl E-155-8 loaded in it, and at first, mostly at lower volumes, it seemed scratchy and almost blown. However, the longer I played through it, it improved gradually and now seems perfectly fine. Could it be that after sitting around for a long time, (years possibly) that it just needed to get moving again? Or, should I expect problems with it down the road?