I guess the expander on is with the switch letting the resistor disconnected and not going to ground right?
Correct. you can even discard the 47k resistor if you want permanently the expander is ON. (as downward expander noisegate)
IF you want it to NORMAL you need the 47k plus the SPDT switch connected to the ground so the expander is OFF.
IIRC when the expander is OFF and set to NORMAL it is MUTED or as in bypassing the circuit I can't recall.
Mine is always exp ON and no switch. I like to clear up this also with Larry.
Let me just add on CALIBRATION procedure, what I meant by expander ON/Bypass OFF is the DPDT or 3PDT footswitch to engage the effect. Mine is DPDT with millennium bypass and LED indicator.
Do the calibration on those trimmer with just clean guitar on both effect ON and Bypass OFF not with that SPDT and make sure the sound is the same (unity) when ON or OFF.
After calibration, test it with your HIGHGAIN or DIRT box with single coil or just make an awful noise or hum then let us know.
Oh about the 10k trimmer was just a question also by Larry if this can be made or replace with. You can experiment buddy and tell us also about the SPDT when it is set to NORMAL.
Cheers,
Roger