buy an audio jack at radioshack or from the internet, move the washer/nut from that one to the graphic fuzz.
or bring the pedal to the hardware store with you to get the sizes/whatever; most places i’ve gone have been pretty handy with getting me the right size stuff if I bring in the actual project. if there is a plastic washer [or you want to add one] and don’t feel like finding the right size, try cutting your own from the lid of a can of coffee/nuts/oatmeal.
