My solution to a problem where a metal trapezoidal piece (that fits in between the front standard mount and rail) was coming out because a set screw that was holding it in place had been lost. I've contacted Marflex for a more elegant solution of getting a replacement set screw to hold the piece in, but in the meantime, a modified paper clip with black tape is ugly, but works!

The Heinrich Hack 'n Clip ;-)
Attachment 46239