"Adjustment: set the 1k "Abuse" pot halfway. Play though it, and adjust 5k preset until "gating" just stops. That's it!
You'll find that it has plenty of output, that the "Abuse" control gives a good range of colour, the "Sparkle" control has a very wide range and the sound is remarkably reminiscent of early Jeff Beck (certainly not a bad thing!).
Put small value capacitors from base to collector of the middle two transistors - start with 47pF. This "smooths out" the sound a lot, but reduces the treble available.
If you have radio interference, put 100pF from base of the first transistor to ground.
Experiment with the capacitor values in the tone control - the 8n2 could go as low as 3n3, which would give a ridiculous range of treble control!
Increase the value of the 47k feedback / bias resistor - try as high as 470k. The gain will rise, the touch sensitivity will disappear, and it will become a high gain screaming monster! "