stuck seat belt
#3
You say there isn't enough slack - am I to assume that its all the way retracted?
Its probably something to do with the retraction mechanism in the seat belt's reel-thingy. Ive had the issue in my balt once or twice with the back seat belts, and in the F-150's at work the passenger that you are describing, but it would lock at about 4 inches of slack from being taunt & fully retracted. Working in the shop on the F-150's -- I played with the belt, sometimes this worked cause you just have to be smarter than the belt safety feature, sometimes it doesnt unlock when it should.
I ended up having to take one F-150 & my balt in for my Drivers belt cause of issues with the mechanism, they replaced the belt because of it.
If you are within miles, I would swing by the stealership and have them look at it, I would say see if you could look at the reel for yourself but major safety things (like the seat belt & LATCH, etc) I don't touch - I let a machanic deal with it...
--Cow-Chick--