Mine will "twitch" almost constantly on the Yaw axis even if it's sitting stationary on a table. Will also make a grinding noise when trying to turn on the yaw, then jump to where it should be about a quarter of a second later. Did everything I could think of... reboot, calibrate the compass, upgrade/downgrade the firmware... occasionally I'd get lucky on a flight, but nothing was ever permanent.
This looks plausible, but I'm concerned about the grinding noise and any damage done to the rotor, so may end up sending it back to the shop anyway (they've agreed to do an exchange.) I don't detect any resistance when attempting to shift the motor, but it does feel awfully tight against the battery, which is awfully tight when it goes in. Phantom is otherwise perfect and am thinking long term of going with longer landing gear and the washer/longer screw solution mentioned above.
One thing to note - am not 100% on the role of the ribbon cable connecting the gimbal to the drone. Assumed it was just to send video and provide power, but if it's able to communicate am not 100% on where the 'brains' are. Am hoping this isn't a board in the Phantom 2 causing it to spaz.