Uh-Oh I just looked for a replacment part on realoem.com, for the top dash vent and its part of the entire upper dash panel. I had removed it when I added chrome to my interior and snapped the clips that hold it in. I should of not of removed it and just taken the two pieces off that allow you to access the center speedo screws. Now its loose as heck, I'll have to go to my Mini dealer and ask parts if I it can be orderd seperate. Just venting.

 

Surely you can add a little dab of Silicon seal in concealed areas to stop the looseness.

 

Can also try putty or strip caulk. Easier to clean up but not as solid as silicone.