The method I have used on these is to carefully cave in one side of it with a screwdriver and a hammer. Then you can yank it out. You can pound like hell as long as you are not hitting the lip the seal sits in. Yake it out, clean out the old RTV, and put a new line of RTV in, and carefully tap in the new seal. A flat block of wood helps spread out the beating. Go slow, and make sure you are getting it seated in straight.