What I have done in the past is just what 2000TCMC siad. Make the track as loose as possible, line up a window with the end of the slider, remove holding nut and bolt from front, then gently with a sharpened piece of oak used as a chisel tap (the oak with a hammer) the edge of the slider toward the back. Once it gets past the window you can grab and pull with pliers. Before you put the new one on put a little antisieze compound on rail. It will make it easier to take off next time.