My Phantom won't fly straight in Home Lock or Course Lock. It will fly straight when this switch is in the off position. I have connected it to my PC and have done an advance calibration and also have done a calibration on the TX. All seems well. When I first got it a few months ago it flew straight forward, backward, left and right in all modes and now it flies at an angle following the front left motor (drivers side) and will track forward, backward, left and right on that axis. It is set to Quad-rotor X but seems to be flying like a Quad-rotor I. Anyone have any ideas on how to fix this problem?