Here is what a Cutoff sweep from Min to Max sounds like in my Polysix for now. You will hear quite a bit of noise in the form of fluctuations in the signal. In the Min position at the beginning, what you hear is probably some Cutoff or VCA or MG bleed as calibration wasn't up to par.
https://soundcloud.com/yashn/korg-polysix-cutoff-sweep
Got to check the traces around IC18-2 (Res) and also try to follow the rest of Johannes's instructions.
Yash