Calling all Phantom experts! A few weeks ago, my Phantom fell from 30-40 feet straight down. I had failed to tighten a prop which dropped in flight. I was able to pick up all pieces. One arm in the shell was badly bent, deformed, unrepairable, one ESC slightly bent. The compass cable was torn, the gimbal damaged. I replaced the shell and the compass cable. After those repairs I did a check flight and noticed a motor was lazy during the startup sequence. While it might be the one that got damaged, I wasn't sure. I replaced the motor (new motors with black caps which is tightened counter-clock wise - it is a clock-wise motor) but the symptoms were the same (startup sequence, not necessarily visible in flight) [youtube]http://www.youtube.com/watch?v=zCipH6z20QE&feature=youtu.be[/youtube] At first spin, that motor and prop turn slowly as if working hard (though they're not hitting anything) if I go full throttle, the Phantom takes off and seems to fly ok. Of course I am paranoid and I feel it's not flying as well as it used to, Att mode tends to drift more I think and GPS mode doesn't loiter as well as I remember it did. Also, I can't fly more than 4 minutes with a Gimbal, 9.5 minutes without any payload 1) Where do you think that lazy motor (before full throttle) issue comes from? 2) I think that DJI ESC don't need calibration but this looks just like its calibration is off, no? 3) Am I paranoid about the higher battery drain you think? 4) Is it ok to run one black prop motor, provided it's the right rotation?