Noticed at practice last week a slight clicking sound but chocked it up to the not so great PA rig where we practice. Noticed it tonight but louder. Coming from my GK amp. Not through the amp into the speakers. Something in the chassis. First thought was something in the fan but the frequency is to low for that. I was looking at the amp and pressed down on the top rear part of the chassis and it was subdued. Nothing noticeably loose. Maybe the fan mount? No loose screws externally. Very strange. Wondering if anyone has experienced this and if so, I could fix it myself? Not an expert but comfortable with electronics. Filling out a factory service request now and have no doubt GK will take care of me. Just wondering if anyone has had this issue? Amp still works fine. Just worrisome mechanical noise.