It helps to lubricate the rubber seal. I use silicone spray. Start by prying the seal from the roof on the outside and spraying lube behind it. Now move to the inside. start at the upper front corner, roll the seal away from the roof and press out on the glass with your hand flat. Once you get the window started out, work along the top. It's a good idea to have someone on the outside to catch the window. When the top and sides are done, lift the window and seal up off the bottom flange of the roof.