Just got a Big M cab model M2212f. I know it was assembled in L.I. I've read the whole deal. Its a vertical 2 x 12 with folded sides. A bass player previously owned it, it could be bass or organ. Strange part is there is obviously 2 different speakers inside. One shiny, one not. Easy to say one was changed, but.... The back has nice tolerance completely covering the back, no seam to open the cover. Then there's no visible screws. Anybody seen this before?