I had to replace one of my motors and the EC board recently. Once I replaced it, I realized I ordered the wrong thread direction for the self tightening props. What I did was to remove the top of the old motor thread/shaft part and put it on the new motor. It was not hard to do and flew perfectly. Remove the e-clip and little washer/spacer. The pull apart. It takes a little force to pull apart as the magnets are what is keeping it together.
Ron
Ron