Thank you for the great write up! A couple of additional points:

a) when removing the three clips that hold the rear of the headliner to the roof, VERY GENTLY PULL / WIGGLE THE CLIPS USING A PLASTIC TRIM TOOL. I used very narrow needle-nose pliers to pinch the gold colored clips for easy removal from the slots in the roof. TAKE YOUR TIME WHEN REMOVING THESE CLIPS.

b) also make sure your two drain holes in the front are not clogged. They are very hard to see because of the wind deflector popping up when you open the sun roof. I also did the front drains by removing the covers on the "A" pillar. Check and unclog the drain holes behind the front jack points. These are often clogged.

c) It is a good idea to clean/lubricate the sunroof rails at least once or twice per year. It is amazing how much dirt/pollen/ debris can and will accumulate. The cost and time to replace / repair the panoramic roof in the E53 can be substantial. Dirt in the rails is not helping preserve the sunroof mechanicals.

d) I also use 3M's silicone paste on the sunroof rubber and it has worked well for me for many years.

e) be careful not to over torque the clamps you will place on the rear drain hoses.

Hope this helps.