I have Russian Big Muff Pi that I just bought on eBay, but I haven’t been able to make it work. The bypass works, and when activated the light comes on, but it will produce no sound. I used the same set up (even the same battery) with my USA Big Muff and it works fine. I opened it up to check for loose wires, and I don’t see any, but I’m no electrician. The guy I bought it from swears that it worked fine 10 minutes before he shipped it. Any ideas? Thanks!