Ok, that story got me thinking, why don't trainers come standard with spinner nuts like Dubro or Higgly spinner nuts? It's so much easier to change props, and with a trainer, that seems to happen a lot.

(ok, on thinking about it, I know why. The spinner comes in the kit and will fit most any engine, a spinner nut has to have the correct threads. Still, if you find yourself changing props a lot, ditch the plastic spinner).