I have here and original big muff. It’s the original from 1969; the kind that isn’t really a pedal but is something you plug into the face of your amplifier. I was hoping some nice people out there could please send me a very simple diagram or photos even. I’m no good with schematics at all. I’m still in the learning process of trying to understand them. When I try to turn it on, I get no fuzz at all. The only thing that functions is the knob, when you turn it clockwise it raises the volume and vice versa. Your help will be very much appreciated.