About 3 weeks ago I bought a Gibson GA 15RV. At first it sounded awesome. Clear, warm, and smooth. Then a few days after owning it I noticed a lingering note (ghost note?) on one particular note in the middle of the fretboard. In the meantime I hooked the amp up to my 2X12 cabinet, which disengages the internal speaker, and the mystery sound was gone thru the extention cabinet. Last weekend I tightened up some screws and whatnot in the Gibson cab and found that made the noise worse. So logically I loosened the ones I tightened and it seemed to go back to the normal thing with said mystery sound. Therefore, I've played the amp thru the 2X12 cab since then. This evening I decided to give the internal speaker another try and at first there was the mystery noise, then noise on more notes, and finally major noise sounding like someone pulling and scraping a chair across the kitchen floor. I plugged it back into the 2X12 cab and it sounds wonderful. So I'm ASSuming it's a internal speaker issue. The speaker in question is one of those Vintage 30 Celestions. Any idea from anyone on what's going on here? Thanks in advance!