We only get 12 months out of the rubber impeller here in fla. The rubber dries out and the spring pressure in the cup goes down. If you take the impeller out of the cup and the blades are still bent, replace it.
Got to also remove the shift shaft. Install the prop nut and the washer on the shaft. Heat the unit to about 800 deg. Then with a slide hammer, grab the prop nut and give it a few raps. If it doesn’t budge heat more and repeat. If no luck heat more.increasing the temp between each hammering episode.