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Cheers! Found a solder bridge a couple of traces away from Q4. Solved the problem and now its working. Many thanks.

I built a Grapevine from madbean's board. I'm not getting it to work and I've spent hours trouble shooting an am getting very frustrated. The bypass works fine. When the pedal is engaged it is only has a very faint sound and no overdrive. I used an audio probe and traced the issue to Q4. I've replaced the transistor twice to no avail and the pads on Q4 have lifted from re soldering so I had to do a bit of surgery. Here are the voltage readings for the transistors.

Q1 G-5.46, S-1.15, D-0
Q2 G-8.87, S-5.46, D-0
Q3 G-8.88, S-6.01, D-5.44
Q4 G-0.52, S-0, D-0
Q5 G- 8.87, S-1.50, D-0.52
Q6 G-8.88, S- 0.52, D- 0

Any ideas as to what might be wrong? Only subs are I used 47nF caps instead of 50nF caps and I didn't have 200pF cap for C8 so i put two ceramic 100pF caps together in the same hole. Works fine with the audio probe and doesn't seem related to Q4 on the schem. Are my transistor voltages wrong and any ideas what the problem may be? Any help would be greatly appreciated.