I hope you got this fixed already. Mine did the same thing on the passenger front. The tube that holds the worm gear is broken. I tried many different fixes from glue and tape, to a coupling designed for pvc pipes, then coupling and glue. I ended up replacing the entire regulator with one i bought at advance autoparts. If I remember correctly, it only cost about $80.
Its a very simple fix.
Remove Interior door panel. 2 screws (one in door handle and one in door pull hand grip) then it pops off if you pry with a screwdriver starting at the bottom near the speaker.
Remove plastic weather liner. Its held on by a tarry black substance that is reusable. Just peel carefully around the edges.
Remove speaker. four screws.
Disconnect window. Pry two c clips out from the sides of the window. pop the window away from you, raise it, and tape it open.
Remove the window regulator. six bolts (2 top of track, 1 bottom of track, 3 on motor) Squeeze the hole contraption through the hole in the door.
Installation is reverse of removal.
Good luck.