Some IC-s at the input were shot, and also a few solder joints were cold.
The gain stage clipping was always on, produced a nasty hiss/crackle and the compressor didn't work.
Works well now!
This remains now a hobby, but I used to do: Handmade clones of Guitar & Bass Effect Pedals / Effect modding / Rewiring and Guitar Setups+levelling+refrets / Amplifier Repairs / General Audio Repairs