Could also be a broken plastic piece in the sliding jaw. Seems the slider breaks on the rt rear window on 126's one most often. I though my 560 had the rt rear window broken out when I bought it, found the glass in the door when I opened it up to replace the window. The plastic had shattered away from the single rivet allowing the entire window to fall into the door.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.