Before you go nuts, take the flywheel off, and carefully take a fingernail, and see if you can pick that galled plastic off,……don’t panic if the cage ( encoder wheel ) pops off the flywheel,…..it’s designed to pop on & off,…..but I’d leave the encoder wheel on the flywheel for the added rigidity to attempt a clean up,…..I’ve seen this before, and I’ve been able to clean off the galled up plastic,….
Pat