OK, I mail-ordered a 5MM helicoil kit and it arrived today. Worked great. Took me a few minutes to drill out the hole and install the helicoil. I have re-installed the prop and all seems well. Can not fly due to bad weather now. Bobby Wilson says to torque these 6 bolts only to 37 inch-pounds. I don't have a torque wrench that will go that low (this is less than 3 foot-pounds). But I would estimate that I was torquing them to at least 5 foot-pounds. I have had trouble with them loosening up and then they all shear off. At 37 inch-pounds it seems to me that they will loosen up within 5 minutes of running. I'm using a wood prop.