I have a 99 540 with Xeon seems like the ballast is loose and shakes around a little if i grab the back of the wire i can move the ballast assembly a little i know it has to move to auto adjust but is there a way to take out the slack.
When i hit a bump you can see the light shake slightly the other side is nice and snug. Is there a way to fix this?

That's not the ballast.

http://forums.bimmerforums.com/forum/showthread.php?t=322712