I just bought an old used Ampeg B2 combo, and I can't figure out how to take the grill off . It has one of the older grills that is made of a black mesh material. Does anyone have any suggestions? I already tried pulling on a plastic tab that I thought would pull off the grill, but instead it turned out to be a piece of plastic trim, which I had to cement back on. Does anyone have a clue how to take this thing off?