Today we took apart our falcon 500 because it felt a little stiff in some spots we though that the bolts might be loose again. When we opened it up the bolts were all tight and there was still a stiff spot. We then proceeded to look around in the motor to see what might be causing it and we found this…
As Jon said, your best move is to contact Vex support.
I am a brushless motor designer, and have some experience with the type of magnet retention failure shown in your picture. Very often they can be repaired; however, I strongly recommend against attempting the repair independently. This one is on Vex – let them guide you, whether it is by authorizing a return or by detailed repair instructions.