I am working on a Kohler Courage 19hp in a Cub. It won’t spin. I can move the flywheel about 1/4 to 1/3 of the way around and it stops. Not a metallic stop but a softer stop. I pulled the spark plug and piston is moving. Removed the valve cover and valves are moving, push rods not bent. Looking for ideas on my next move.. pull head or engine top. I work on a lot of riders but don’t normally teat engines apart. This unit has been sitting under a tarp for 2 or maybe 3 years. Ideas? I am tempted to scrap the Kohler and re-power the Cub