I have a convertible and the leather wrapping on the rear headrests have shrunken a little bit, exposing the white plastic beneath. They were like this when I bought the car and it looks terrible (it's got to be from the over exposure to direct sunlight along with the owner not treating the leather). What is the best way to stretch them back so they cover the headrest? I am thinking some sort of pliers after I "treat" the leather or something but I have no idea. I am about to sell the car and want to do it myself. Thanks for any help/ideas.