Recently my Dunlop 535Q (the original 18v version) has started to periodically produce a loud, high-pitched squeal, sort of like a kid's space gun. The frequency of the squeal varies with the position of the pedal, so I can "control" it (?) with the wah. Very strange. Interestingly, once this starts, it does it even when the wah is clicked off, so that moving the pedal still makes the noise, though at a lower volume than when the wah is on. I can sometimes get it to stop by disconnecting everything and starting over, or by giving it a good solid kick. Has anyone else experienced this or have a clue as to a possible cause or fix? I'm using the original Dunlop 18V power supply, in case that matters. Thanks!