Reporting question for Effects Pedal Kit - MOD® Kits, The Rock Bottom, Bass Fuzz

Product:
Effects Pedal Kit - MOD® Kits, The Rock Bottom, Bass Fuzz

Question:
Hi, I built this last year and had a lot of fun doing it. My blend knob stopped working. No clean signal comes through - it just lets more or less fuzz volume through. I don't know much about electronics so I looked for any obvious loose connections but didn't find any. Wondering if where to start on trouble shooting