Sounds like the metal channel which the felt channel rides in has come loose. The front one in spot welded to the leading end of the door and to a bracket at the bottom, inside the door. The rear one is held on by 2 screws at the bottom of the trailing end of the door, and one screw at the top, inside of the door which is "fun" to get to.

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission