WARNING: This page is about a different car, the 2004 Pontiac Sunfire, 2004 Chevrolet Classic, and 2004 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Channel Plate Checkballs
Courtesy of GENERAL MOTORS CORP.
Install the seven checkballs into the proper locations on the channel plate.