I have a mach .15 engine and I hate it. the one way bearing is in the crank case first of all so there no chance of the bearing grabbing. I can remember how many times I have had to replace that pull start rope because it is so thin. the other day the spring came out on me.... i spent about 1hr getting the darn thing back together. I Have to take the pull start off every time I want to start it. when it has already been running if I zing the pull starter REALLY fast it will grab for a tiny bit and it usually starts.

If the bearing is in the pull start housing I have found that if you put a hole in the top of the housing and one in the bottom, I shoot a jet of carb cleen doun in there. It makes it grab quite nicley.