I only just discovered what makes these tick.
The car had non-functional headlight adjusters and I assumed they were cable operated (that would be sensible, right?)... Well, amazingly these mongrels are "powered" by a fairly viscous silicone oil using parallel plungers in the dash controller and the most common (desired) setting is full extension. Not surprising they fail - in my case, the brass plugs on each adjuster had cracked the filler neck.
A bit of Googling revealed these were fitted also to Porsche 928 models at one time. The owners thereof, generally complained when they failed but didn't seem to do a lot about repairing the system. And we reckon Dee owners are tight. I reckon they are fixable (provided seals are OK) but there is some plastic welding needed. A compression sleeve in brass around the filler piece would stop it splitting again.
Peugeot / Cibie Hydraulic Headlight Adjusters (405 etc)
Moderator: RichardW