Take a look at this instructional video and learn how to replace your bumper guard/grommet strips. This should be done for a number of reasons. One reason is if the bumper guard has worn through and you are now hitting graphite when you scrape it on the ground. Another is if the grommets are coming apart and the string has a chance at touching the frame. Or if you wish to add lead tape in a more conspicuous manner, replacing the strips and guards will help.