The pretensioner locking mechanism is probably jammed if you can't pull the belt out of the retractor spool. Sometimes rapid jerking on the belt will un-jam and release it, as Bubba B stated above. Also, if you remove the retractor spool it might be possible to disassemble it enough to expose the pretensioner gear lock and maybe fix it if you can find what is causing it to lock prematurely. But I think I would just try to find a similar Crown Vic that is being parted out and buy the belt and retractor assembly. I expect the belt is an integral part of the retractor assembly and it probably won't be too difficult finding a similar Crown Vic that is being parted out but it might not be so easy finding one with seat belts matching your interior color.
