Make sure you have a copy of JH's calibration procedure and that you let the circuit warm up for a while before attempting to calibrate it. Note that I'm using LM13700 chips so you might get different results if you are using LM13600 chips.
1. Filter Cell Frequency Adjustment
Set all pots fully counter-clockwise. Don't plug anything into any of the jacks. Set all the filter switches to LOW PASS. Set the CLEAN/DIRTY switch to CLEAN. Set R62 (V/OCT trimmer) to the middle position. The MIX and RES switches are of no concern.
Follow JH's instructions for setting the trimmers for the six filter cells. Start with 3, then do 1, 2, 4, 5, 6 in that order. Trimmer R84 (for cell #3) is particularly finicky, you will have a very tough time setting this to exactly -7.5V. Don't be too concerned with it because you will need to change it later on anyways.
You will need to repeat the process for trimming the six filter cells several times because changing one trimmer seems to affect the response of the whole circuit (it took me four passes). In other words, after you trim cell 6, go back and trim cell 3 again, then do 1, 2, 4, 5, 6, then go back to 3 etc. Don't be too concerned about getting the exact voltages the first time through, anywhere from -7.4V to -7.6V is good enough for the first pass, you'll gradually hone in on the sweet spot with each pass. By the fourth pass you should be reading very close to -7.5V for each of the six filter cells.
Once you've finished trimming the six filter cells, you'll then need to readjust R84 so that the FREQ pot is effective over its entire range. There is no right or wrong way to set this, you just need to set it to whatever works best for you. Ideally, you'll want the filter to cut off all frequencies when it's fully counter-clockwise and to pass all frequencies when it's fully clockwise. If you're building one Varislope, then you can probably just set R84 so that the filter cutoff matches your other filters as you rotate the FREQ pot. If you're building several Varislopes, you will likely want them to be matched to each other.
Apply a 30 Hz sawtooth wave to the IN1 jack and turn the IN1 pot 75% clockwise. Turn the MIX pot fully clockwise. Keep all other pots fully counter-clockwise. Set all filter switches to LOW PASS. Set the CLEAN/DIRTY switch to CLEAN. Listen to the signal at the OUT jack (and hook it up to an oscilloscope if you have one). Turn R84 until the signal at the OUT jack completely disappears. Turn the FREQ pot clockwise, you should start to hear something (or see something on the scope) once the FREQ pot is greater than 10% clockwise. Verify that turning the FREQ pot fully clockwise opens up the filter all the way and that you can't hear any of the upper harmonics being removed from the sawtooth.
When I had R84 set the way I liked it, I measured -14.00V (plus or minus a few mV) at each of the six filter cells when the FREQ pot was fully counter-clockwise. When the FREQ pot was fully clockwise, I measured +0.460V (plus or minus a few mV) at each of the filter cells.
2. Resonance Adjustment
There's no right or wrong way to set the resonance trimmer R6. The following factors all affect this filter's self-oscillation: RES pot, RES switch, SLOPE, CLEAN/DIRTY switch, ALL PASS vs. LOW PASS switches. You'll just have to try out different settings to see what works best for you. In the end, I turned R6 fully clockwise (maximum resonance) since I can always use the RES pot to turn it down as required.
3. Sample & Hold Adjustment
Hook up an oscilloscope to the LFO Output jack. Turn the RATE pot fully clockwise. Turn the WAVE pot to the S&H position (about 75% clockwise). Adjust R137 until the waveform reaches +/- 5V at it's maximum extent. Note that the S&H circuit takes a while to get going (mine takes at least 30 seconds to stabilize after initial power up), so don't try to set R137 immediately after turning on the power.
4. 1V/Octave Adjustment
To set the 1V/OCT trimmer (R62) you'll need to have a voltage source that can output 1.00V to 4.00V in 1V increments and a reference oscillator. I used an MOTM-650 hooked up to a MIDI keyboard for the voltage source and a digital keyboard (outputing a sine wave) as the reference oscillator. Setup the voltage source and reference oscillator so that 1.00V corresponds to a frequency in the 100-150 Hz range and 4.00V corresponds to a frequency in the 800-1200 Hz range.
Don't be too concerned about getting this filter to track accurately over a dozen octaves, three octaves in the mid range will be fine. I got mine to track quite well over 100 to 800 Hz and left it at that. This filter does not have temperature compensation, so the tracking will drift a bit: don't spend too much time on this.
Connect the voltage source to the 1V/OCT input. Set all the filter switches to LOW PASS. Set the CLEAN/DIRTY switch to CLEAN. Set the RES switch to NEG. Set the MIX and RES pots fully clockwise. Set all other pots fully counter-clockwise. Listen to the filter output and turn the FREQ pot to make sure the filter can self-oscillate in the 100 - 1200 Hz range (or whatever range you are going to use with your reference oscillator).
Set the voltage source to output 4.00V (or 3.00V), call this the "high note". The reference oscillator should be playing the "high note". Listen to the filter output and turn the FREQ pot until the filter output is in tune with the "high note" (no beating).
Set the voltage source to output 1.00V, call this the "low note". The reference oscillator should be playing the "low note". Listen to the filter output and turn R62 until the filter output is in tune with the "low note" (no beating).
Repeat the above two steps alternating between setting the "high note" and adjusting the FREQ pot with setting the "low note" and adjusting R62. After 5 or 6 passes you should get the filter to be in tune with both the high and low notes.
Note that changing R62 will affect the filter's frequency response for all control voltage inputs, including the FREQ pot. Once you've got R62 set, check that the FREQ pot still works well over it's entire range. If not, adjust R84 (one last time) to suit.