If the 4 screws across the top and 2 on bottom are already tight, try the following.

I'm not sure what you call them, but make sure both "clasping barrels" are fully extended "out" when you close the glove box door. My right side one likes to stick "in". I'm pretty sure it pushes "in" rather than making purchase with the clasp when you shut the door. Make sure both are fully out by pushing against the one on the opposite side if one is stuck. See bad pics (first pic - stuck in. second pic - extended out).

Also, if you're like me, and didn't know this, there's a little shelf above the main box that doesn't move down with the box when you open it. It's secured (rather loosely) from the ceiling of the compartment. This little shelf I assume is a owners manual slot. Without weight in the slot, mine rattles against the ceiling. There's probably a way to tighten it up, but a quick fix is: insert owners manuals (or a fat wad of something else) back into slot to shore up the play, effectively eliminating the rattle. (Third pic).



All quiet now. Give it a look on yours if you have the same %$&*#@ rattle.