It looks like this:
And should be clipped to the shaft that comes out of the bottom of the motor, holding it in place and preventing any movement. If it's not there it's worth having a good look inside the aircraft shell to see if it's hanging around in there somewhere. If it's loose and can move around in flight it could potentially short something out. Sometimes they get pulled up into the motor itself by the magnets - worth pulling the bell housing off and having a look inside.
And should be clipped to the shaft that comes out of the bottom of the motor, holding it in place and preventing any movement. If it's not there it's worth having a good look inside the aircraft shell to see if it's hanging around in there somewhere. If it's loose and can move around in flight it could potentially short something out. Sometimes they get pulled up into the motor itself by the magnets - worth pulling the bell housing off and having a look inside.
