I have ordered replacement adhesive plastic stone guards from Pelican - these are the clear plastic bits that mount just ahead of the rear wheels. The original stone guards on my car are a bit yellowed, and one has a black streak across it that I cannot get out, and so felt it was time for a refresh. Any advice on how to get the old ones off? I was thining maybe a hairdryer, and applying "Goof Off" or similar product around the edges to get the adhesive loosened up, but I would appreciate any advice from others who have done this before. TIA.