Haynes manual lists it, hard to explain without pictures, but basically, u need to get the clamp on the selector, then put the gearstick into reverse, then i can put a pin horizontally through the linkage (from underneath the gear stick), you then select reverse on the box by using a screwdriver or allen key, rotated fully clockwise and then pushing in, tighten the nut, unloick the gearsticxk and thats mena be it (mine took a while ) especially as the linkages are always worn

This make any sense to you?