When you apply a lot of torque to a piece of plastic that is sandwiched between a prop and drive washer, then the plastic can very well give way. If you think that's ludicrous, then you don't understand physics. When my saito blew it's spinner, it was at full throttle--not much backfiring going on at full throttle. You sure seem to know a lot about spinners, while at the same time having questions about them in other forums.