I've had this ongoing problem for quite a while. The output of my Cirrus seems to change randomly as I play. The normal, great, punchy sound sort of drops in level. It's kind of subtle though. The volume is still there pretty much, but the punch and meat drop down. It doesn't fluctuate rapidly. Over the course of a 4 hour gig, it might change 2 or 3 times for an extended time period. Plugging and unplugging doesn't change anything. I've already cleaned the jack too. I'm pretty tech savvy and have already opened up the preamp cavity and visually checked things and measured the battery voltage on the board while shaking the wires to make sure that wasn't the problem. I get about 18.5v with my newish batteries. I can start replacing the IC, diodes and capacitors on the board for a few bucks and my time, but I wonder if the pickups could be a problem as well? Does anyone have any ideas? I don't want to upgrade, I just want to fix this one.