Hey, I have a show tommorrow, a big show for us, and my Hartke 3500 head, just started crappin out on me. Im using a 8 ohm avatar 4x10 with it, and its not the avatar, because i've used another amp head that i have with it, and it sounds perfect. When I play with the head.... it kind of sounds like a really crappy cable, or loose output jack, its not speaker overdriving, just fuzzing, and crackling. Its not the bass, i've used several basses, with the same outcome. I've changed speaker cables, intrument cables, everything. Its the head, for sure. What do i do? Does it just need cleaning? Please give me some advice! How much should i expect to pay if it does need a cleaning? And what else could be wrong with it? Thanks for your help!