I have a 2011 M37S with the Rear Sun Shade. It has been problematic since the beginning. I finally decided to do something about it.

If your Sun Shade makes a loud clicking noise, the gearbox has worn teeth and must be replaced. Ebay is a good place to start.

If your Sun Shade goes up but not down, the arms are getting stuck in the up position.

The fix is very simple and inexpensive. I spent $1.78 plus tax at the blue Home Store.

I used # 6 and # 8 automotive speed nuts. I like the #8 nuts better as they are bigger.

The pictures explain everything. The Speed Nuts prevent the Arms from traveling too far in the upright position.

12+ up / down cycles and all is good.

Sometimes the simplest solution is the best solution...

I forgot to mention my local dealer quoted me $1,100.00 to replace the Sun Shade. Would the new Sun Shade have the same issue of over extended the arms? My money is on "YES".

Now the sunshade is making the clicking sound again. Not happy. Currently I have it up and the motor is unplugged. Has anyone figured out how to permanently fix this?

I had to replace mine, bought a very good used one on EBAY it was 135 bucks.
took the rear seat and deck out it was pretty easy.

Update us in a year. That's how long my EBay replacement sunshade lasted.