OK, here's "the rest of the story." It may have learnings for all W124 owners so pay attention!

Turns out that the recent breakage of the sunroof mechanism was caused by old damage in the headliner panel, which they did not catch and replace last September when they did the overhaul. In the W124, the headliner panel (124 780 02 40) has two fabric "side flaps" (I'll call them) that act as wind blocks when the sunroof is popped open at the rear. In my headliner, one of the side flaps was worn and the other was actually broken loose at one end. This end jammed in the track on one of the few occasions when I actually opened the sunroof, causing one of the bridges to break.

This is a much better hypothesis than "bad sunroof motor," which neither I nor the service manager were happy with. The good news is that the part is still available and the dealer will install it for free and not charge me for the broken parts, which is reasonable since they should have caught the headliner problem last September.

The bad news is that the headliner has to come from Germany and even with 15% MBCA discount will cost me $500.

In the meantime, I can have the car back this afternoon with a working sunroof but no headliner, returning the C550 loaner, which was fun to drive but I wouldn't want to pay for its fuel on a regular basis. Over the long weekend, I plan to remove the old, cracked dash, replace all of the climate control vacuum pods, and install a new-to-me, uncracked, freshly painted dash. Once the new headliner arrives, the car will go back in for a day and I'll have a good sunroof.

Those of you who have an original, still working W124 sunroof might want to pull the headliner panel (fairly easy to do if the sunroof will open) and inspect those side flaps for wear. It may even be possible for a clever DIY-er to repair the side flaps rather than replace the whole thing. If that prevents breaking the opening mechanism, it's worth whatever you have to do.

I'll try to get pictures of the damaged headliner.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970