Awesome!, I had run out of possible causes!
This is why I listed this many moons ago as this sort of thing could be resolved earlier with this Picture (y)
https://forum.pedalpcb.com/threads/important-supplying-pictures-when-an-issue-arises-with-a-pcb-build.7081/
By your description in the Original post satying it's farty, it sounds like a Biasing issue so Check the 4 transistors voltage as listed by Robert above!
You definately got the listed 10K at R15, The pulldown resistor at the end as that is a known problem on plenty of circuits with 100K ???
10K - Brown, Black, Black, Red, Brown.
I love how remorseful Josh was that the Designer up & died on him so he didn't know what the Parameter was so with clever planning , they measured it!!!
I don't own any JHS & don't plan too!
I came across this today doing some research on the Superbolt.
Joshua Heath Smith has designed very little, modified a lot!
https://www.freestompboxes.org/viewtopic.php?p=265977&hilit=jhs+superbolt+version+1#p265977