Hey,
I am having the exact same problem. I have a hunch to think its a faulty switch but I am not sure, and something is definitely funky with the ground connection because touching it alone results in a large buzz. These switches can sometimes be the first thing to go on a pedal like this. I will try and switch it out and we will see how that goes, just have to find those switches i ordered off ebay.
Good luck, let me know if you get to the bottom of it.