(the pictures are copyright by me - Patrick Joericke, ask me if you want a agreement)
Also read the TTSH Calibration guide or ask me for support.
Triangle , the original settings from the factory was totally wrong - symmetry(Spike)
use a scope and check your waveform and correct this by turning the trimmer TRI Symmetry
Thats not a Sine wave !- wrong settings from factory
Purity - bends the TRI to a Sine wave - after this check the voltage to 10VPP (adjust the gain)
Filter Frequency, the Filter closed at 100hz instead of less 10hz
Move 1 VCO to top in the VCF mixer and try to close the Filter, the signal must stop at 10-20hz Initial Frequency settings., not by 100hz or more, just turn the Trimmer as shown on bottom picture. (read the TTSH calibration guide too, to understand what you do)
Modded VCF with 1% premium LCR caps in the 4012 and matched 2.5% to 1% tolerance in the 4072 VCF.
I used sockets to make the LCR cap footprint compatible with the PCB RM5 footprint.