Hey Billy, thanks for your reply!
I am really talking just about the second Opamp (IC1B) here. With a gain of 3 it hardly pushes the Ge-diodes into saturation. R15 is just a summing resistor which has nothing to do with the gain of this stage, so changing it would just make the preceding signal louder and push the second opamp into saturation (which is not what we want, bearing in mind that the original had an even higher headroom in this stage!).
I know it’s not supposed to be a high gain distortion pedal, but between 3 and 100 there’s quite some difference! The circuit around IC1B uses basically the same values as the original, so it should at least be in the ballpark….