Thanks for the kind words, sorry for the late reply
The silver knob is the oscillator pitch, the first white knob is volume. There's a choice of insertion point into the fuzz circuit for the guitar signal controlled by a rotary switch (the second white knob), offering differences in tone and response. The spring loaded button is wired to add a resistor to the oscillator circuit giving the pitch of the oscillation an instant drop, switching it in and out quickly gives a step filter-ish sound. Then there's a true bypass switch.
The biggest problem with this (and all Hex-Schmitt based synths that I've heard) is it's extreme ear-raking harshness at higher osc frequencies. This is certainly one application of this sort of circuit where a Lo-pass filter would come in really handy, one day I've promised myself I'll build that extra circuit and incorporate it into my guitar. Space is really at a premium in there though!