The sliding jaw you show does appear to be in the right spot, although it appears to be a different design than the original one you show further up the page. Are you sure it's the correct part? It should be a snug fit, but not tight.

Before putting in the new window, it would be a good idea to find out what bound up and broke the one you have. I'd suspect it jumped a track!

When they do break, it's pretty alarming. I had a rock come in through my front passenger window in a construction zone once. I thought I'd been shot! Talk about a loud noise! BOOOOOOM!!!!!!!! Had that car for another 4 years and was still finding little shiny diamonds in places when I traded it in...

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]