Ditto Quicksilver. The HID's vertical aim sensor is usually the issue when the headlights droop downward.
The video below is of an e39...but the e38, e39 & e53 HID headlamp levelers are similar (except for the adaptive left/right movement found on some e53s)...the video goes underneath to show how the leveler is attached.
I've also seen some e53 DIYs where the arm has gone in the wrong direction when the suspension was lifted...and the leveler connection just needed to be corrected back to the right direction of movement...click this link to a thread that discusses this issue:
http://www.xoutpost.com/bmw-sav-foru...-problems.html
Click this link to watch video: Xenon Headlight Leveling Connection-rod BMW 525 E39 - YouTube