My rattle came back a couple months ago. I ended up removing the wiper arm assemblies & cowl. The design seems to be lacking any rattle control between the slot in the cowl and the bottom of the windshield (there is a tape strip on the top, but nothing on the bottom).
The solution that seems to be working well is to completely clean the bottom of the windshield and wrap some electrical tape around the bottom of the windshield along the entire length. Clean the slot in the cowl and re-assemble (the electrical tape will be completely inside the slot so you will not see it after re-assembly).
So far, no more rattles.
