I have a 2002 2dr Accent Hatchback. The passenger side seat belt "spool" (near the floor - behind the interior panel of the back seat)is messed up. When someone puts on the seatbelt,sometimes it locks and won't release. It just keeps getting tighter and tighter. (I know it is designed to "lock up" in the event of a sudden movement - but then after that it won't release) Seems like a ratcheting feature is broken. Is this an expensive repair?? Thanks for any help.