W140 Rear Seatbelt Retractor

[oldsouth]

I am having problems with my rear passenger side seatbelt. It will not pull out right anymore. Sometimes you can gradually pull it out but most times it will pull only a few inches and lock up. I had this problem about 6 years ago and the independent mechanic could not get the new one I purchased to work right, so I took the car to the dealer to fix. It has worked up to now and it is doing the same thing again. I bought a new belt, took it out of the box and it is locking up just like the old one so I did not install it. Is there a trick to get the new belt to work right without locking?