After pulling the gearbox apart on my motor (1962 28hp) the prop shaft has small groove in it. Its right where the prop shaft seal rubs against the shaft and I'm not sure if it?s normal or I should be worried about it. The groove is very narrow and even, it almost looks like it may have been machined into the shaft. I just don't want to waste my time repairing the gear box if the prop shaft is worn out