OKey, checking with the audio probe, I've find the next, but I'm not completly sure about whats normal or not.
IC1.1 TL072 All leads sound.
Path 1 going to R19:
R19 Sounds.
IC1.2 TL072 Leads 5, 6 and 7 sound
R4 Sounds.
R5 Left lead sounds neat an right lead is wet and little bit distorted...