I have a 2009 Honda Accord Sedan with a moonroof.
The deflector keeps working loose and vibrates at high speed.
It looks like the deflector is fastened (I use that term loosely) to the roof with four metal clips that screw into the deflector but only hook to the roof panel.
Does anybody have any suggestions for how to tighten these "fasteners" enough to abate the vibration/noise?

 

This one might help you-- v6performance.net/forums/6g-honda-accord-technical-discussion/11780-re-moonroof-sunroof-noise-rattle-fix.html

 

If it's like mine you can add lock washers to keep it tight.