Good evening. I am a new CL55 owner, buying a silver with grey 03 with 59k on the odometer. One thing I noticed were the dim low beam headlights which was surprising since the car uses Xenon bulbs. I ended up buying two new blubs and when taken apart, the old ones were not installed correctly. I fiddled around for about an hour trying to get them back in properly, even looking on the forum without success. Then I finally figured it out. The best way to correctly install and seat the blub is the following process:

1. Insert the blub into the headlight housing with the u notch in the upward position.
2. Install the black ring next placing the bottom leg out at the bottom of the housing and spin clockwise to lock the ring in place.
3. Connect the wiring to the igniter now because it will be more difficult once assembled.
4. Take the igniter and position it that the small tab between the four arms goes into a small round circle on the black wheel.
5. You’ll noice a small yellow arrow showing the twisting position of the igniter to close. Twist clockwise.
6. Test the headlight.
7. Install black covers.

I kept trying to install the light as a complete assemble which was the reason the blub wasn’t fully seated in the 1st place.

If I take it apart again, I’ll take a few photos.