250 pro xs with silver lower unit. When i spin the prop by hand their is a grinding noise like prop is rubbing the housing. This is a new motor that has never been run it's on the showroom floor. Is this normal? It is not the ticking noise its more like a small grinding noise like the prop is rubing on something. I have done this with the reg black lower units and hear nothing but first time i have looked at the silver lower units and spun the prop by hand. They said its normal with that lower unit. Is this correct??