My 68 CDR has developed a problem. I spoke with Mike at KCA NOS yesterday and got some advice on various tube issue scenarios, but I don't think it's a tube. I swapped out all but the rectifier tube and had no luck. Basically the amp is running about half the volume it was. It is lifeless and one dimensional sounding and feels flat and sterile under the fingers. It had such great sparkle, depth and a 3D-like quality before. As I thought back over the time I've used it in the last month, I recalled a studio session where we wanted to use tremolo but I didn't have the footswitch to activate it. The house engineer grabbed a couple of footswitches he had lying around, but none would activate the tremolo. The next time I turned on the amp, I immediately noticed that something was wrong. Does the circuitry of the footswitch jack affect the master output of the amp? I'm wondering if plugging in the wrong footswitches at that studio could have caused some damage or is behind this issue in some way.