I had to replace mine, so I'll give you an idea of how to do it. First you'll have to remove the door panel. Be careful so you don't permanently mess up too many of those panel pins. Next take a small punch and knock out the center of the aluminum rivet holding the actuator to the rear of the door. Then (being VERY careful) either take a chisel/screwdriver and knock the rest of the rivet out, of Dremel the rest of it and use a screwdriver to pry the rest of it to pieces. The actuator should then fall out quite easily. The rest is self explanatory.
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Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch