I had just finished installing the new 9" props and thought I'd check all the Allen screws on the bottom of the Phantom. Once I finished, I happened to spin on of the props and noticed it wouldn't spin well. It was making a metal on metal sound. I thought at first that I had overtightened a screw to the point that it was making contact. So I loosened and finally removed the 4 allen screws holding the motor down. Then I noticed a tiny, tiny piece of a metal shaving that the motor's magnet had grabbed. As the motor spun, the metal shaving would get stuck and cause the motor to stop spinning. To fix, I removed the c clip on the bottom of the motor and lifted the housing off and removed the shaving. The moral of the story is, don't go down to your dirty shop table and work on your Phantom without cleaning up first.