The TH-VCO1 has four precision trimmers to calibrate the sine shape and pitch tracking.
Using an oscilloscope, adjust the offset/symmetry and shape/roundness of the sine wave using both trimmers. The waveform will be at roughly 10Vpp.
Use another already calibrated oscillator and tune both to the same low frequency with 0V CV with the Coarse and Fine Knobs on the Panel. Feed both oscillators with 1V, 2V, 3V etc and adjust the frequency trimmer to match the octave of the reference tone. If you don't happen to have a second oscillator or it isn't calibrated right, play back a reference tone on a computer and switch it's octave up and down depending on the voltage you feed the VCO1 (1V=1 Octave up, 2V= 2 Octaves up and so on), trim the VCO1 till it matches the corresponding tones. Wether you are right is up to your ears: if you are close you should hear a beating interference between both oscillators – this beating or phasing will get slower the closer you match the oscillators to each other).
If the pitch is slightly off at higher octaves, use the HF trim to compensate.