I have a 2000 996 C4. It has about 130K miles. About a month ago, the motor from the sunroof began to slip and so I looked at the manual and decided that I could do this myself. I know, big mistake. However, removing the old motor I found the white plastic disk was missing some of the teeth. I purchase another used one off Ebay, and installed it. The motor is strong, but the sunroof is opening and closing only partially. I call the party that I purchase motor from and they tell me they checked it and it worked fine before listing it. Not wanting more problems, I am at Festival of Speed in Fontana and am talking with a guy with a race converted 996. I ask him if he has any parts that were stripped from the race car and he tells me he has the sunroof motor which was working excellent. He sells me the motor and I install it and the motor is strong, but it won't close all the way. Is there a part that I am missing which tells the motor what to do Any advice in this problem is much appreciated.