Catalinbread Dirty Little Secret Build problem

[Mezmerize]

Hey everyone,

I'm having a bit of trouble building a Dual Channel Catalinbread DLS for a friend.

I am using the 9V only layout from this site: http://tagboardeffects.blogspot.com.au/2013/04/catalinbread-dls-mkiii.html#comment-form

So far I got the first channel and all the switching wired up. The bypass signal is working fine.
When the pedal is switched on, there is an audible low frequency hum, which sounds like there is a grounding problem i can't find.
The output volume is also extremely low and the volume pot somehow doesn't do anything. All the other pots and the switch work fine, though.
The weird thing: The output volume changes when I move around the circuit board on the inside of the enclosure . It comes nowhere near unity level, but it definitely changes.

I am using J201 transistors btw. They worked fine in the single channel version I have built for myself a while ago. Thats why I decided not to use any sockets this time. 
I hope thats not the problem.

I would be very glad, if anyone around here has an idea about whats going wrong with this thing. I can also post gutshots, if thats necessary. I haven't found any soldering flaws, though.

Anyways, thanks for your help! 

[mth5044]

You could take voltages of the transistors and use an audio probe to see what is happening to the signal.