Just having the retainer screw "snug" seems to work fine when using an electric starter. My Big Stik 60 has an OS 91 Four Stroke and a Tru-Turn spinner. The cone has never moved when using the electric starter. I went to the hardware store and bought a bag of 10-32 screws in a bunch of different lengths. I prefer finding one that works without cutting, but that's probably just laziness on my part.