I built a Ross Comp with Keeley mods, 5-knob job, but I'm having troubles. I don't have a schematic, just the stripboard layout from tagboard. It has a blend knob, and the clean side of the circuit works fine. However as I turn the blend knob to the compressed side there's no sound coming through. Now if I crank the clip knob and really strum hard it will suddenly come on crazy loud, then, just as suddenly switch the sound off. I've gone over the placement of components several times and knifed the gaps between the copper strips but can't seem to get this right. Any suggestions?