I have a Chamberlain 9950 screw drive garage door opener. It appears the rack (81C168) is broken in half because there are two black parts on either side of the trolley (41C4677) that were about 8 inches apart and are now about 3 feet apart.

Is this common / possible? If so, how do I get the two parts out of the rail and replace it with a new one?

Thanks for your time.

Mark