despicable merc

I was cleaning sunroof and found 2 broken peaces in the closing mechanism. My sun roof works fine. The only thing one touch close doesn't really work im mean it closes automatically but when its just about to be fully closed it retracts back to the middle. It's being doing that for a while. I thought it was some sort of safety feature or rail needed to be lubed. Anyway im curious now what are those two plastic peaces.