Do you have a pic looking more at the prop and level? Be interested to see where it actually enters and how it's going over the heads. Have to remmeber air is not going to go through the fins (which is optimal) unless directed... much like electricity it will find the path of least resitance.

Normally I find that engine start to loose power and then die if they are run hot..

Have you checked your battery under load? Pref. a 1 amp load just to see how it's holding?