WARNING: This page is about a different car, the 2007 Isuzu i-370, 2007 GMC Canyon, and 2007 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: View Of Crankshaft Balancer Sealing Area & Belt Ribs
Courtesy of GENERAL MOTORS CORP.
Inspect the crankshaft balancer sealing area for grooves, nicks, or burs (1).
Inspect the crankshaft balancer belt ribs for dents or damage (2).
Replace the crankshaft balancer if damage is present.