OK-I fixed it (see second paragraph).
My large old friend pulled the damned belt all the way out in my '02 and it won't retract. There is a tiny bit of play and I've taken the interior cover off to get at the mechanism. I can't see the mechanical locking mechanism, just the belt going onto the reel.
OK, I found out how to fix it. Remove the interior panel-it just clicks in so it will pull right out. With that pulled out of the way (I left the top fastener attached) you'll see a black plastic cover over the belt reel. That pops off as well and you'll see 3 yellow plastic wheels with teeth. At the top there is a white plastic lever. Push that lever to disengage the lock and tug the belt. After several tries I got the belt to retract as usual. Button it all together, snap the panel back and go drive. Good luck.
Tom