Quite quite a simple job. First remove the interior trim by lifting under it with a screwdriver (put a cloth under it to protect the bodywork).
The unit is held in place with a large plastice nut. Before this can be unscrewed remove the small crosshead screw that is there to stop the nut vibrating loose. Unscrew the large nut and pull the unit out from the outside of the car. Relacement is a reverse operation.
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