I just got a deal on some new props to try on the Scarab. I had old kiekhaefer 3 blade cleavers (think Miami Vice era props) solid hubs. The new ones are Bravo 1's I got the correct heavy duty stainless hub inserts with the props that sit below the thrust washer face about 3/16". I took the hubs out and made sure I had all the snubber strips in place and greased everything up. If I hold the prop shaft still, I can rotate the prop about 3/8" back and forth. It is not rattling around. I figure I would get a little rotational play between the splines of the shaft- to the castle insert- to the hub insert- to the prop, but I want to make sure this is normal.

the stainless hub insert is a PN 850821-1. The hub inset sits about .160 below the prop hub

Never really checked before for play, did check a new hub off the shelf and a used one from my boat both did not have really any play, tightend to seat hub and than loosen. hope this helps

Do you have the proper thrust washer behind the prop?