I was belting in a car seat, pulling out the whole strap to get around the unwieldy beast when it locked, fully extended. I am unsure whether I can unlock it, or if I need to purchase a new retractor. It is the rear passenger side, I have yet to pull out the seat and give it a look over. Any advice is appreciated.
You might be able to release it by pulling a bit and see if it will let go. You have to pull very gently. If that fails, I think it is off to the junk yard to get another belt.
Call an auto upholstery shop and ask if this is an easy fix by them and a ball park price if you are not able to get it released.
Avoid the dealer at all cost. A friend of my wife had this happen and the dealer insisted the car needed a whole new belt assembly. The husband took it to another mechanic who discovered a piece of peanut jamming the mechanism and removed it for free.
@Docnik has the right idea. Look for something holding the belt in place. I have a car that does that if the seats are too far back. If there is nothing there, the inertia weight inside the seatbelt retracter may be stuck. If you can gain access to it, smack it lightly with a plastic or rubber hammer to see if it will release the belt.
Try a quick sharp pull out and then let it recoil. Seatbelts are made to lock when pulled all the way out, so you can install a car seat. You release it like you used to release a window shade.
Make sure whoever does the repair knows what they are doing, since the seat belt is a very important safety device. An auto upholstery shop for example – as suggested above – wouldn’t be on my list for this type of repair. My children’s safety would be far to important to having somebody who’s main job is using a sewing machine to debug a seat belt mechanism.
I’ve never had that particular problem, but I had the opposite problem one time with my VW Rabbit, where it wouldn’t extend at all. That turned out to be a problem with the inertia gadget, which I was able to spot just by removing the cover to the unit. But those mechanisms are more complicated now, so it might not so much be within the realm of diy repair any more.
I would agree to just try to pull it, bang it, and unjam it. But I’m not sure anyone except the dealer would have anything to do with it for liability reasons. I wore a buckle out once and had a heck of a time getting a shop to re-sew the buckle on and pretty much signed my life away before they would do it. On the other hand, the Olds dealer gladly replaced a rear belt at no charge-same reason, liability for the brand.