I have a similar problem and I'm thinking of using marine tex. http://www.marinetex.com/Marine-Tex_how_to.html#Anchor-How-5677
How to restore the strength of loose or stripped fasteners:
-Product: White or Gray Marine-Tex Epoxy Putty 'The Mighty Repair Kit'
-Materials: 80-100 grit sandpaper, a drill-bit slightly larger than the original fastener hole, WD-40 or other silicone lubricant, wrench or screwdriver for removal after cure
-Conditions: Minimum 60¢ªF temperature, 48 hours to fully cure at 60¢ªF, 24 hours to fully cure at 70¢ªF
-Read instructions on product packaging. Drill a slightly oversized hole, slightly shorter than the new fastener, to remove any soft or deteriorated material. Clean debris from the hole. Apply a little penetrating oil or a silicone spray (like WD-40) to the new fastener to act as a release agent; wipe off excess film. Mix Marine-Tex White or Gray and fill the hole 3/4ths deep. Apply a small amount of Marine Tex to the fastener, being sure to fill in around the threads. With a slight twisting motion, insert the fastener in to the hole and allow the epoxy to cure for the full 24 hours. Marine-Tex will have the threads cast into it, and the fastener can be backed out if necessary. A wrench or a screwdriver with a little extra elbow grease may be needed the very first time the re-inserted fastener is removed since it will stick the first time it is backed out.