My Rena Xp3 impeller is still spinning, but will not spin when the cap is on. Do I need a new part?

My filter turned off on its own one day, and I haven't been able to get it restarted since. The impeller cap still spins, the magnet seems fine, but when the impeller cap is on it does not spin. If I leave the cap on loose, the filter seems like it wants to work but is not strong enough to pump water through.

A: If your filter is more than 4 years old your rotor probably does need changing. However, I really think you have something going on with the impeller cover and/or rotor/impeller that it causing it to bind once the impeller cover is installed. This can happen if the basket lid is not seated properly or is warped or if the bushings on the ends of the rotor/impeller are no longer holding the rotor/impeller completely verticle.