I had one - exactly the same sort of problems.

It starts easily by hand when it is cool, but not when hot.

No problems with an electric starter when hot.

The solution: let it cool down before restarting by hand. Same as other suggested.

I ran a 10x6 APC on mine (same plane).... never tached it, but it pulled it around without problem. It idled a bit better with an APC prop due the increased weight (inertia) of the prop.

I had the spinner "spin off" a few times as well. Early on, it was because I was trying to start engine when it was flooded. The piston would not go through compression (hydraulic lock) and the result is that you end up unwinding the prop. Once I got the the hang it.. no problem.

As for the little ridges, just score the back lightly with a knife to create some new ridge.... yup, I did that too.