They are motors underneath the headlamps and a pain to get at (headlights out = bumper off). If you look on the top of the headlamps you'll see a hole with a white plastic screwdriver socket inside, that will manually adjust the headlamps up and down.
typical problems with the auto adjust are:
- french electrics stop working
- linkage pops out (if you put ign on you should hear motors under headlights whirring).
- adjuster unit dies (poor quality).
Steve Powell, October 2008