Ah, the seatbelt recoil thing may be dirty, I'd try to clean it. It may help.
If it doesn't, then you gotta swap it. Makes me question used, because they are usually from wrecked cars...so how was the belt effected? I don't know. New works, but awfully pricey.
So, yeah, I'd try to clean it up first (if possible) and see how that goes.