The relevant parts involved in the vco output are:
C14 = 560pF
R18 = 10k
R19, R49 = 10k
and Master tune potentiometer = 10k to 50k depending on how extreme you want it to get.
Make sure these parts are correct and has the right value. (different values will make for a different frequency spectrum)
Now for the tuning -
1. make sure the glide is off (toggle in center position)
2. Set the Master Tune pot to zero (all the way counter clockwise)
3. Set the octaves faders so that only the second upper octave is on (to have a clearer signal picked up by the tuner)
4. Hold the highest key down and use a tuner to measure the pitch
5. rotate the trimmer pot related to this key to tune in the correct note
Then repeat #5 with the rest of the keys, one by one as you go, until you reach the lowest note.