Here's a post I made on another forum about a similar problem. It was made in early 2007. We have another 15,000+ miles on the coach and everything is holding up fine.
"The grill on our Adventurer is held in place by 2 latches and a bracket behind each headlight assembly. Several years ago the right side bracket came unglued. We carried it in a storage compatrment until early this year when I heard about an adhesive others have used with success.
I bought a kit of SEM brand #39537 Weld-Bond Adhesive at a local body shop supply house and reattached the bracket. So far all is well. This summer we went over 12,000 miles through Canada and Alaska and it's still holding fine.
Some may say 12,000 miles isn't enough of a test but on the roads we were driving I would compare it to 30,000 miles in the lower 48. It got a real test on the Top of The World Highway. It was 110 miles of bone jaring, teeth rattling gravel washboard.
The kit consists of 2 tubes (hooked together to fit into a special applicator gun) of mixible adhesive and 2 mixing tips. It sells for about $47.00. The "special applicator" costs another $95.00 but you can easily adapt a standard caulking gun to do the job.
I unscrewed the round plunger plate from my caulking gun, made a flat plate with 2 holes (I believe 1 1/2" on center) and a third hole directly on center (where the original plunger plate attached). I screwed 2 carriage bolts in the outer holes with the heads facing towards the tube openings. Then assembeled the plate to the plunger, slid the adhesive tube in place and went to work. The special tip assures both adhesives sre well mixed as they are applied.
The product is meant to be used by body shops when they need to glue plastic outer panels to metal framework. The most common applications are for door skins and fenders. It's easy to work with and has a working time of 60 minutes in 70*F weather.
The whole process took only a couple hours including removing and preparing the grill, fabricating the bracket, and applying the adhesive. I let the glued assembly sit in the garage over night just to be sure there wouldn't be any problems."