Thought I would share my experience with a problem I was having with my P2V, and the solution. I replaced a motor on my P2V on a hunch that it was the cause of a problem I was having with the quad drifting when yawing in GPS mode. Thankfully, the new motor eliminated the problem. My Vision only has about 10-hours of flight time. I noticed the problem was very sporadic early on, but became more easily repeatable. I was getting 15 to 20 foot of drift when I rotated/yawed the quad any significant amount. If I didn't offset the drift with control input, the quad would eventually stabilize on its own. While trouble shooting the problem I ruled out IMU and compass calibration. The quad has not crashed and the props are balanced and in like new condition I did notice early on that I had one motor/prop that would come to a stop much quicker than the other three on shutdown. It also appeared to have less RPM at idle on startup. I couldn't feel any friction rotating the motor, in fact, the culprit motor had less magnetic resistance than the other three. After installation of the new motor I did an IMU calibration and compass dance. I did a 15-minute test flight this morning and could not reproduce the drift problem. I soldered bullet connectors on the wires when I installed the new motor to simplify future replacement (pic below). I'll install the connectors on the other motors when or if I have reason to replace them.