Just came in from a flight and i've noticed my phantom is turning anti clockwise all by itself. I noticed from my previous outing as well it was starting to drift a lot to the left but now I think it was because of this self yawing (is that a word?) motion. So no hands on the throttle and it does a 360 turn in about 15 seconds. Does this in GPS and ATTI modes. Down wind, up wind always turns anti clockwise. I have only recently lightly sanded all 4 props because of what I would describe as tiny bits of fur particles. Did about 3 compass calibrations (the S1 switch up and down) but before I do a computer based calibration is it something else I should be considering first? I have also mentioned in another thread that one of the motors has been 'sticky' from day one. When turning on the props 3, get going but the rear right may take an additional second or three before it joins the rest. Bird has never been in a crash. Any idea of a diagnosis?