Plexi With Trimmers Debugging

[freshmex18]

Noob pedal builder, first time poster.  I've successfully built a few pedals from here but this one has got me stumped.  I've torn it down and rebuilt it twice and even started on a fresh board on the third build.  I've got sound but absolutely no gain.  I try to bias the J201s with the trimmers but the voltage at the drain jumps from ~4 to ~8 with the tiniest tweak of the screw.  I've checked and rechecked every component and I don't see any errors.  I know my soldering isn't pretty but there are no bridges.  I've gone over and over it with a knife blade.  I'm at a loss.  If anyone has any advice, please help.

1 - http://tagboardeffects.blogspot.com/2013/09/plexi-drive-with-trimmers.html

2 -  

3 -  a clear description of the problem: Ex: i have signal when the pedal is bypassed, but when the pedal is engaged there is no signal, or the pedal has low output and doesn't get to unity volume, etc.

4 -
Q1  D 4.80v  S 0.05v  G 0v
Q2  D 3.62v  S 0.05v  G 0v (one tiny nudge of the screw sends the D voltage up to 8.31)
Q3  D 4.53v  S 0.04v  G 0v


Thanks for any help you can offer