One of the most common causes of a sunroof operating slowly or not at all when it's cold & then operating somewhat normal when warm is that the grease on the cable & in the cable tube is old and full of years of Crud! No matter how much MB grease you put underneath the sunroof tracks/rails(no point putting any on top of track) the problem still exists. Kent Bergsma at: **************.com has a Sunroof Service & Repair Kit complete with MB grease, sunroof tube cleaner cable w/brush & excellent illustrated step by step repair manual. He also sells on Ebay. I am not associated with Kent in any way other than being a Very Satisfied customer. My 1985 190E Sunroof would open slowly & then not close completely. Anyone who has tried to close a stuck sunroof knows what a Pain that is! You would not believe the amount of Yuch inside the tracks & cable tube. After following his directions & pics, my sunroof now operates just like new. My 2 cents.