If you've still got grinding then there's something else still wrong. Other bearing, bad bearing parts inside motor, bent rotor shaft. The wrapping is carbon/Kevlar thread with expoxy holding it together like a high strength fiberglass. I definitely wouldn't go cutting any of it off and would be prepared to rebalance if attempting a repair.
Idk what Castle has as far as motor repair capabilities, wrapping and balancing rotors may be something that's only done in their factory or for prototypes. I know Castle wasn't keeping many spares after the motor sale. Neu might be willing to help you out if Castle can't.
If you've still got grinding then there's something else still wrong.
I agree. Sounds like you're out of luck. I recently sent in a 1520 because the wrapping was wearing off. They said they will replace it with a 1717... that's good service and I'm not knocking it but I would've prefferred my 1520 back