Trying to put something on to stop/slow further detioration is probably a good idea. Not all epoxies will stick to plastic, so look for one that mentions it in it's directions. Also, epoxy will probably not take a dye very well, which means you'll have to paint that area. If it's brittle I think plastic welding would cause more harm than good so your options may be limited. I've got quite a bit of time with various epoxies, resins and plastics, but in an aircraft environment, so don't take my opinions as gospel. Good Luck!
bill