tlp,
The point of calibration mode is to individually adjust each filter side (high and low). In this mode only one or the other filter side is working at at time depending on how the harmonic mix knob is set. It sounds like the low side is working properly…being that you get a woolly tone when the harmonic mix knob is set to the “low” side. Is the high side of the filter working when the harmonic mix knob is set to the “high” side? If the high side isn’t letting signal through then that would explain the woolly tone.
If both sides are working then adjust the trim pots until the brightness comes back and the woollyness is diminished.
What did you mean when you said “the issue persists when engaging the tremolo”? Are you getting a woolly tone when the pedal is bypassed as well as engaged…or do you mean just when the depth knob is up?
-Brach