Wow, I have some extra parts! I can see that those extra parts are what was probably blocking the water flow.
One being the green hose looking tube and the other the Black hard plastic tube piece. Both were stacked and fit over the prop shaft. Weird that someone would do this.
Note: I did not take the rubber prop shock absorber out of the prop for this picture.
I see a bunch of daylight around the shaft where it comes thru the cover. Without pulling a motor apart, I don’t recall there being a seal here but I’ll bet you that’s what the previous owner used the bit of rubber hose for.