"Rick, are you sure the prop h
"Rick, are you sure the prop hasn't spun on it's hub? and it's actually slipping out of gear????
The hub itself (and prop shaft) may be turning fine, but the blades are not moving (slipping).
Place a mark on the hub (close to the prop-shaft splines) and an ajacent mark on the prop itself. Give it a crank up, if the marks end up out of line, the hub is spinning.
The hub is usually encased in a rubber sleeve which is then pressed into the prop. This prevents gear damage should you strike something hard enough to stop the prop dead. The rubber does however, rot/wear out/shrink over time which can leave the prop slipping as you increase rpms and it loses "grip"..."