You're not doing anything wrong, you just got some bad props. It can happen with any brand of prop. I personally have had the same problem you are having with Master Airscrew and it's one reason I don't use them anymore. Instead, I use APC or Graupner Profi when I'm not flying a wood prop. OTOH, I've seen posts from others stating they rarely have problems with M.A. props yet they can never seem to get APC's to balance. You might want to try contacting M.A. directly and see if they aren't willing to try and make the deal good for you.

John