W124 Door Rattle
I've been dealing with a really annoying door rattle in my '95 E320. It's on the driver's side and it sounds like it is coming from the door latch area. It sounds "metallic", and it almost sounds exactly what it sounds like if you tapped on the silver-colored metal part on the inside of the door frame that door latch latches into. I seems like the latch is rattling against that metal piece, but I can't say for sure. I can't tell exactly, but it seems like the tension on the latch on the problem door is about the same as the passenger side door (I thought maybe there were some springs loose).
Additionally, that door seems to be a little harder to close and open than the other doors.
I searched around on the forum here (found tons of ideas for questions I had for other issues, thanks everyone!) and have heard mention of a Door Check Strap (and saw the replacement procedure), but I don't really know what that's even for. What is that for? Anybody got ideas on the rattle?
If there's other information that I have left out to help troubleshoot, please let me know. Thanks.