I just bought a Super Tigre G51 and I'm using a C.B. Associates spinner and a Zinger wood prop. My question is, With the back plate on, the prop will not go all the way down to the back plate. It goes all the way down the threaded shaft but at the bottom there is a step on the prop shaft that is a little bigger in Dia. How do I get the prop to go all the way down to the back plate.