I had to repair one of these hood insert when I pulled our insert checking for rust... I cleaned both surfaces with light sandpaper and used two part epoxy (for Plastic) to reattach the mount. We have had no problem with the repair (done spring).

Under that hood insert you also have two drains in the corners, check those out also. You may need to clean out the drains and the 6 in tubing (we replaces tubes were pinched).

Hope this helps...