I have recently buildt a F550 from an ARF kit.Everything is set up by the book and configured with recommended settings, but I have a prop-killing problem. Motor 5 is "misfiring", stopping for a half second now and then, randomly, and not in any set frequency. It is stopping more often when the motor is getting less power during flying backwards or rotating. First thing I plan to do is redo the soldering, but could this be something more serious like defective ESC or motor? Anyone with good suggestions for me? Have been flying a Phantom 1 for some months so I am not totaly new to this, but it is my first hexa and first self buildt project.