EBike 36v 500w

Looking for a rear hub motor. The EBike was givin to me as a gift. As I started to fix it Batteries/ Lights/ wiring/ I found out that the rear roller clutch does not engauge. I was wondering if their is a replacment part for it or should I just get a new rear outter hub with sprocket? And if anyone has one hear to sell by all means please let me know. I would really like to start use this bike for more "hunnie to do's" list... Thanks for your support.
Jake