I have a QSC PLX 1202 that rattles badly. I've search as much as I can find. I found a thread that shows there is hope for eliminating the rattle, but I can't get the cover off. Feel pretty dumb I can't see any more screws that allow it to come off. The cover is loose and lifts partially from the back but it seems to be still attached in the front, but I can't see how. Help please.