W203 Seatbelt comes undone!

[Smatt]

My c230K coupe's drivers seatbelt comes undone while driving along. This has happened intermittently on a number of occasions. Initially, I presumed I had not properly secured it, but it's happened a number of times when I am convinced it was secure.
Anyone had experience of this & is there a fix or does it need replacing?

Thanks

 

[markjay]

My c230K coupe's drivers seatbelt comes undone while driving along. This has happened intermittently on a number of occasions. Initially, I presumed I had not properly secured it, but it's happened a number of times when I am convinced it was secure.
Anyone had experience of this & is there a fix or does it need replacing?

Thanks

I had this on another car, it turned out to be a tiny glass fragment stuck in mechanism (the side windows was smashed a couple of months earlier), and it took a while to get it out... not sure if it helps though.

 

[Smatt]

Thanks for that Markjay. The screen was replaced a couple of years ago, so it could be glass (or something else). I will see if I can dismantle it, or at least jiggle it upside down a few times....
Matt