I have a 9.9 hp Nissan 2 stroke on a 14 foot semi-V hull. The motor runs good but I am losing RPM at WOT I am certain the hub in the prop is slipping as it only drops RPM after I turn sharp and the RPM's wont come back from time to time. The prop I have on it is a 3 blade 9.25 dia. 9" pitch...