On the (factory installed) sunroof, there's a black plastic piece on the roof that moves (up and down) to receive the glass when it closes. To enable movement, there's a hinge on each side (of the opening). The hinge appears to be white metal (painted black in my case). One of these hinges has broken and I'd like to replace the entire piece (as I believe it's all one piece). So I can order this piece, any idea what it's called and how it comes apart to replace? Any help would be most appreciated. (I found no other topic on this particular issue during a forum search).