put a 500k in replacement for the 205 k pot, go to radio shack and get a bunch of different caps. tape the caps to a firm piece of cardboard and make 2 very long leader wires with a clip on either end, unsolder your present cap from the pot lugs , plug into your amp, start with the first cap on your board and clip the leaders to it, clip the other end to your pot lugs (where it would solder to ) and play for a while, take notes as to the tone and repeat with all the caps until you find the one that cuts the frequencies you desire, time consuming, but that's the only way to do it unless you like doing a lot of soldering and unsoldering with the tone bleed caps....Greg