I have adjusted the gain, that is fine now. Sound appears to be the same with effect engaged or unengaged. On the middle pin of the depth control I have 0 V all the way counterclockwise, increasing to 5 V at full clockwise rotation. Q1 and Q2 appear to be installed correctly rounded side toward the optocouplers. In calibrarion mode I have basically the same sound with harmonic mix all the way over either direction.
Don