Oh man, the pitch to voltage section is over my head. And the series of six invertors? WTF! On the ESP board, VR1 is another of those offsets on a voltage follower op amp, TL081. My guess is VR1 is for trimming the zero output state. VR2 I have no idea.
On the filter, my MS-20 has the Korg35s, so no daughter board. The schematic is here: http://machines.hyperreal.org/manufacturers/Korg/MS-synths/schematics/KLM-307.GIF
Those two trimmers near the diode chains are for setting the Max resonance points: the resonance at which the filter oscillates. This should be similar to the FC adjustment procedure. This gives you the ability to change where on the panel resonance (Peak in MS-20-glish) pot will lead to self oscillation. Set the filter Frequency around 5, VCO levels at 0, the dial up the resonance to see where it starts to oscillate. The manual suggests going for 500hz at a level of 10. But if your into the acid sound thing, you might want to give yourself some more room. Say, start oscillation around 7 or so.