That’s great!
In reviewing the previous picture I sent you, I realized I got the jumpers backwards…TP4 should go to R5 and TP2 should go to R4. Sorry! That may be causing your harmonic mix knob problem.
If that doesn’t fix the harmonic mix knob issue then it’s probably because JP3 is damaged and signal isn’t getting through. You can run a small jumper across the blue pads in the previous picture (maybe try this on the solder side of the board if the top side is too cluttered with components). That will bypass JP3.
Good luck!
-Brach