Jeff, it sounds as if something is out of place in your radial pull starter, if it jams when you tighten the thread that holds it on. If you just follow the manual, and make a couple of checks along the way, you'll find it easily enough. Make sure the balls are not out of position - if in doubt, assemble it without the balls, and see if that makes a difference. If all is correctly assembled, it won't make a difference, it will be free with or without the balls. I vaguely recall having the same problem the first time I put mine together, but it was a simple error. Don't forget to inspect the tips of the five sprags for wear.
