It is an easy fix and if done right, the repair will be as strong as the original. Here is where I describe it on my build thread:
http://www.914world.com/bbs2/index.php?s=&...t&p=2841725 and more here:
http://www.914world.com/bbs2/index.php?s=&...t&p=2854777Basically the process is to drill out the old stud and retap the hole for a new 6mm stud. Screw the new stud in with locktite, and glue the plastic reinforcing disc back in using 3M Marine Adhesive Sealant 5200 as described in this thread that really should be moved to the Classics.:
http://www.914world.com/bbs2/index.php?sho...=240803&hl= That sealant is a near perfect match for the original bumper top rubber and forms a very strong bond. The original stud has a button head buried in the urethane that leaves plenty of metal to tap and screw a new stud into for a strong mechanical attachment. Be careful when you drill because once you get through the steel button head of the old stud, the bit will grab the urethane and try to run right through the top of the cover. Use a drill press if possible for better control. If you do run through, you have the sealant handy for a nearly invisible repair. Ask me how I know.
This pic shows a bumper tit stud I repaired but I did a couple of bumper top studs as well. It is a "good as new" repair.