Marshall pedals: JCM800 vs 1959

[jessenator]

I hand write μ backwards, apparently… maybe it's because I subconsciously don't want to write and get confused by s misshapen "n"…

 

[Robert]

C23 is indeed 1uF, and it's a box cap too... but that's not where C23 is actually located in the circuit.

C23 connects to R19, not the tone pot.

 

[Robert]

Just caught this... here's your problem:

 

[Fever2112]

Mystery Solved!