Date: September 13, 2000
I've noticed that on many FD's, including mine, the black trip piece below the rear bumper becomes warped, and fits poorly against the bumper cap.
To fix this, I used a half-dozen "binder clips" from an office supply store. These are thin black spring steel triangular cross-section clips with two chrome handles that allow you to open the clip. I used several of the 1-1/4" size, and a couple of the 2" size near the ends.
These clips can be placed between the screws that hold the black trim piece in place, and will clamp the edges of the bumper cap and black trim piece together firmly.
After putting one in place, use a pliers to twist the "handles", and they will come right off, leaving the clip in place. I sprayed the clips with WD40 before use, to keep the spring steel from rusting. If there is a significant gap between the black trim and the bumper cap, you might want to clean out the groove first, as a lot of sand and grit can accumulate there, particularly near the ends of the trim piece.