I don't know if this will help with your problem, but I used a Tru-Turn spinner adaptor #TT-0835-A on my 32EI. It utilizes a bushing instead of a shoulder on the screw. I got mine from Tower, item #TRUQ4035, $9.99 + $3.99 shipping. It requires a #10-32 spinner screw instead of the one supplied with the engine, but you can pick that up at your local hardware store. It works fine with an APC prop with a hub about 9/16" thick.