I've had a Quantizer from new, and I've just had a 2nd hand one repaired by Doepfer, themselves. Why are they both completely out of whack

Neither tracks 1V/Oct (I played it in concert with my Midi keyboard) and the Voltages jump at different times. They are also out of tune with each other. This happens using a buffer or when driving a single VCO. This renders them unusable.

Can I do anything to fix them