ice_station_zebra,
I'm not sure what I am looking at, but if I understand the pix, you need to re-attach the post that snaps into a grommet. I would start by drilling a small hole, centered where the post goes, right through the silver panel. The hole should be just large enough to insert a short thin grabber (sheet-rock) screw. The screw does not (should not) need to be as long as the post. Scrape away any paint or coatings on the parts, to bare plastic, where the epoxy will be. Then glue the post into position with a
plastics epoxy (not all epoxies are the same).
When the epoxy is fully set, hold the post,
not the panel, in a clamp or vicegrips. Very carefully drill through the hole, and down into the post, with a small drill bit that is smaller than the center shank of the grabber screw (minus the threads). If your drill bit goes out one side of the plastic post, just back off and try again. Then drill the same hole again, with a drill bit only slightly larger than the sheet-rock screw shank (minus the threads). At whatever depth you stop drilling, cut off a sheet-rock screw to that same length.
Get a soldering-iron hot. Begin threading a new grabber screw into the post, holding the post, not the panel. When the screw stops,
don't force it. Heat the screw at the head with the soldering iron, then take of few more turns of the screw, until the screw stops again. Do not use force; this "threading-in" process is an easy-going, gentle operation. Repeat the screw heating and turning, until the screw head of your cut screw will be flush, down to the plastic panel. Remove the new screw, and replace it with your cut-down screw. You can add a washer under the head of the screw, to reinforce the assembly, which I would recommend.
If you insist on having "identical" hardware on each side of the bike, symmetrical, just cut off the head of a matching screw and epoxy it (with a washer) to the opposite side, in the same place as your repair. Hold the screw-head in place with tape, until the epoxy sets. We won't tell anybody.
I do not recommend Harbor Freight junk normally, but you can get a drill-index with dozens of drill bits between 1/4" (5mm) down to nothing, for an unbelievable low price. These drill bits
look like real metal-cutting drill bits. They can drill plastics, if you are careful. This is one job that can use such tools, because you will want a wide choice of drill sizes to be able to match the grabber screw shank (not the threads).
The bottom line here is that you will then have a steel-centered post which secures your silver panel. A spritz of silicone lube will help preserve the rubber grommets, and ease the installation of the posts each time.
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