I have a non-critical issue with my PF500. On the rear panel, there are three buttons related to the XLR out (Ground Lift, 0/-40dB, and pre/post EQ). Recently, these buttons have become recessed into the head. Before, when they were in the "out" position they would stick out 1/4" from the panel and when they were in the "in" position they would stick out 1/8" from the panel. Now when they are in the "out" position they are flush with the panel and when they are "in" they are actually recessed about 1/8" into the panel. I took the cover off and look at the circuit board that the buttons are attached to and it hasn't moved. All of the 1/4" ins/outs are attached to the same board so it's not moving easily. They still function perfectly. They're just a pain to operate. Any ideas? I attached two pics. First is buttons out, second is buttons in. Thanks.