WARNING: This page is about a different car, the 2008 Pontiac G5 and 2008 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Inspecting Gear Teeth & Gear Splines For Damage
Courtesy of GENERAL MOTORS CORP.
Inspect the gear teeth and the gear splines for excessive wear or damage. Remove minor nicks or scratches with an oil stone. Replace worn or damaged gears.