FIRST REMOVE THE BLACK TRIANGULAR TRIM ON THE INSIDE OF THE DOOR BEHIND THE MIRROR.LEAVER IT OFF WITH A SCREWDRIVER PULLING IT OFF THE ADJUSTING LEVER.IT IS HELD ON WITH 2 CLIPS ONLY.
YOU WILL THEN SEE A LARGE BLACK NUT.TO REMOVE THE NUT YOU NEED TO FIRST REMOVE THE SCREW WHICH PREVENTS THE NUT COMING LOOSE.ONCE YOU'VE REMOVED THE SCEW AND NUT(ANTICLOCKWISE AND QUITE TIGHT)) THE MIRROR WILL COME AWAY FROM THE DOOR (QUITE TIGHT,MAY NEED A TAP)
YOU FIT THE NEW ONE IN REVERSE ORDER.HOPE THIS IS OF HELP
n/a saw the answer on another web page!, October 2009