If you remove the piece or the fender you can scrape the paint off in an area that doesn't show. Get some ABS cement at a hardware store. You want the old fashioned ABS Cement the black gooey stuff that comes in the round can with a dauber on a wire under the cap. I've made many repairs on Goldwing plastic which is mostly ABS with this stuff. You'll get a much stronger repair with ABS cement than you can with any kind of epoxy or other product because ABS cement will make a chemical weld to ABS plastic. Test the fender to see if it is indeed ABS by scraping a spot on the underside, daubing a small blob of ABS cement on and once it's fully cured try to pry it off with a knife blade. Epoxies will pop off ABS but ABS cement won't because of it's strong bond with like material. You can even make ABS putty by grinding or sanding a piece of ABS pipe fitting (available from a hardware store) and mixing the dust with ABS cement. Use fairly thin applications of the cement or putty and build it up layer at a time. Overly thick layers won't cure well and can soften the ABS substrate of the fender. The stuff skins over fairly quickly but must be given plenty of time to fully harden. Test it with a knife point or something sharp. When the cement is fully cured it will be very hard.
Before I started using ABS cement I tried many other plastic repair materials in my old Goldwing rebuild shop but none of them came close.
