Maybe you'll be lucky and already have the tool to replace the prop shaft! If you have a spacer infront of the prop take it off and turn it over , a flat piece of metal is snapped over the tool. Just remove the metal and install it in reverse and install the prop and turn counter clockwise if I remember right. On some 25hp mercs the spacer is the tool to remove the carrier of the LU . I didn't have the manual but I'm mechanically incline and its a pretty easy job. Just replace the large Rubber O-ring and the shaft seals , in the carrier. I'd let the shop replace the two seals in the carrier. Its no easy task replacing the seals in the carrier lol I know $300 later i had a new carrier and seals already installed.