Farfisa Multi Tone Booster problem?

[pniven]

Hey everyone, just picked up a farfisa to add to my collection. Replaced all the electrolytics and a couple of bad transistors and the thing sounds pretty d**n good. Except for the top octave, when the 4' tab on the multi tone boost is on. Its a little bit louder than the other octaves, and while each key plays somewhat fine, if i play a chord in that octave, i get a very unpleasant sound that reminds me of a dial up internet connection. Any thoughts?

[burtrocket]

I´m no expert, but my guess would be a problem on one of the tone filter cards, which are located directly under the bass pedal amp/vibrato card on the left side of the oscillators (next to the amplifier).