a Micromesh polishing kit (2000 to 12000 grit cloths) will bring them back to like-new condition (have done several tailights over the years on various cars). It does take a bit of elbow grease but the trick is sanding in one direction, moving up to a finer grit and sanding at a 90 degree orientation to the last time.
If that's a random type sander - you won't as good of a result as the 90 degree method. Run a Google search for Micromesh polishing kits...