So I've had this amp (MG30CFX) for about a year and half now. It's great I love it, wouldn't change it unless it was an upgrade. However around Christmas as my band started to doing a few more rehearsals I noticed a quiet crackling noise coming from the amp, I play on a relatively low gain on the crunch setting and when I playing more clean things (like Sleepwalk by Brian Setzer) its really noticeable when I stop playing, not as much with like my Big Muff or another pedal on. I figure with more movement I probably got some dirt in it. So if that's solved, how would I go about cleaning it? Any tips? Any Feedback on what my problem may be? Thanks!