I was hoping you’d chime in Ray!
I’d noted when I built it many moons ago the resistance on my pot from the beginning of the flat spot to the end, can’t find my notes at the moment, what I noticed is at the beginning CCW it’s low volume clean signal when you get towards the end CW more like a mis biased tranny in that if you hit it hard it comes through distorted and a little clearer and as you get to the very end it sounds more like it should with a kind of intermittent stutter
My next move was to change the transformer with a red fasel thinking I may have got one on the extreme of tolerance range looking at the datasheet the 42MT013 is + or – 10% so I thought perhaps that may cause a problem and could be why a small amount of people get this issue
I thought the problem was either a resistance change i.e the 33K being replaced by the 330K 10 times bigger and then further adjusting the tone pot resistance may cause it or the inductor
If I can find one I’ll look at a fixed wah schematic
I note the guy with the same problem on DIYSB posted that he used a charge pump for 18v and it dissapeared completely, albeit pot lug 2 still crackled when touched so again potentially a resistor change would solve it by allowing more current to flow
Anyway I’ll have a read of RGs wah technology page
Cheers mate hope yer all good