So - just in case - what did you do to modify it? I'm curious....
Mod A; more clarity;
Replace C34 / C13 / C9 / C18 / C43 and C22 with it's better quality replacements
Mod B; tubescreamer:
- Remove C36, C46, C47 and R49; replace this with an 1 uF NP cap (the start of C36 and the end of C46 are so close you can fit in a cap quite easily)
- Replace D4 with a silicon diode
- Replace D6 + D7 with one 1N400X diode
- Replace C28 with a 220 nF cap
- Replace R37 with a 4.7k resistor and run one end to Vref (which is on one side of R51; close. You can use the leftover traces of D6 / D7 to overcome the small distance without short circuiting
- Replace C12 with a 1 uF NP cap
PLAY!!
For guitar I would recommend the change of C28 to 100 nF