I got a batch of these little monsters in. That circuit rocks. Built one tonight, and volume knob wasn’t working at all. I futzed around and found that grounding lug one of the volume pot fixed the issue. Looking at the schematic, it appears that lug one of each pot goes to ground. The boards I received do not have continuity from volume pot 1 to ground. No big deal, it’s an easy fix, but just wanted to give a heads up.
I checked the CAD files, and pad 1 definitely appears to be connected to the ground plane on the back (non-component side) of the board. See the image below. Did you test a new board for connectivity between pad 1 and a GND pad?
Here’s a picture of the screen of my digital microscope (sorry, it’s not connected to the computer atm). This is showing the back of the PCB, volume pot pads.
EDIT: I am not asking for anything, its a super easy fix for me, just a heads up. A year ago, I would not have been able to figure it out, so it might be very frustrating for someone.