Some have had trouble with the "color" version. It seems to make the rubber stiff. Black, and a warm day with the above suggestions, and don't be afraid to "lube, and warm" as needed. In my truck I had some "repairs" that were done to the channel, so I did use a chunk to get the channel open and the proper width. A blunt screwdriver and a pair of large channel locks worked well for me. The screwdriver opened the groove, the channel locks kept the width.
