It's probably NOT the bearings.
I would put it at a 99% probability that the circlip came off the bottom of the propeller shaft. This occurs either after a crash or can just be knocked off during shipping or rough handling.
If you pull up on the prop, does it move up and down or come out of the motor once it breaks the magnetic pull? If so, that's what it is.
In order to repair it, you will have to remove the top shell and put the circlip and bushing back on.
CAREFULLY, turn the Phantom upside down and remove all of the screws (not the motor screws) that hold the shells together. Keep a cloth under it and watch for a very small bushing and/or circlip to fall out....you do not want to lose either. Inside, there will be a non-ferrous bushing that goes on the shaft between the circlip and the bottom of the motor. The circlip goes on the end of the shaft holding the bushing and the shaft in place.
The bushing will (or hopefully will) be loose and rattling around someplace inside the shell. The circlip is most likely inside the motor stuck to the magnets. If not, then it will be rattling around inside the shell with the bushing.
Put the propeller shaft through the motor, place the bushing over the shaft and then carefully push the circlip back into the the keeper groove at the bottom of the shaft. Be careful. If it slips, it can shoot off to the darkest and most difficult location in the room where it will never be seen again...or....it could (most likely) fly back into the motor and stick to the magnets. Always check the inside the magnets first. The circlip is ferrous so it usually sticks to the magnets but the bushing is not and can fall out.
Hope that helps......