I have a small 3.3 HP Johnson and am trying to locate impeller. The schematic I got shows it behind the propeller. When you take the prop off there is no nut to remove. The prop came off with just the removal of the kotter pin and now I am looking at a spindle and a plactic housing behind it that turns the piston when you grab it. But there is no apparent pin, screw or nut removal to go any further? Normally I drop the foot and find the impeller on most motors but this one is funky. Is there a special tool required to go further.