There were several problems with the hydraulic headlight adjuster system.
1. The hydraulic fluid used [silicon oil] degraded over time and lost its viscosity and became more and more like water. This increased the likelihood of a leak.
2. At position 0 [Normal] the system was at its maximum pressure.
3. In the event of a leak the system failed to position 3 i.e. headlights pointing to the ground - MOT failure due to incorrectly aligned headlights.
4. It was technically illegal in some countries.
5. It was only ever available to buy as a complete system from Porsche and even then it was extremely difficult to fit as you would probably have to partially dissemble it [brake it] in order to run the hydraulic lines through the body work.
I am like 'stratfordshark' when it comes to my 928 so I decided to fix mine. Here are some pics. >










[Sorry for big pics - but I don't know how to do thumbs on this system.]
More than 3 years later and the system is still pressurised and the headlights point in the right direction. But to tell the truth - I've never risk using the headlight adjuster or needed to - although I see no reason why it wouldn't work.
I do not recommend repairing this system. [unless you are very fastidious or mad] - It was a very tricky fix and to much to explain here - just do what everyone else does and disconnect the adjusters and whack some self-tappers into the headlight frame to hold it at the correct angle.
