Replacing it involves having a hoist or good floor-jack and stands, removing the front passenger tire, wheel-well shrouds and both drive belts, locating the access port under the flywheel and installing a powerful vice grip to lock the crankshaft/flywheel. Then you unbolt the balancer with a big socket and breaker-bar. After that you need a specific GM puller to pull the balancer off it's taper fit, most standard ones will not work.
Once the balancer pulley is off you remove the plastic "foreign object shield" and then the two screws that hold the (now fully exposed) CPS Sensor with the big gob of iron filings stuck to it's center magnet and replace it, or just leave it (shield and sensor) together and wipe the magnet off with a damp rag until it is cleaned of filings.
For the overall standard shop labor cost, (around $200) the extra $40 for a new sensor is a small added expense, but believe me you really are no/little further ahead with a "new" one. The sensor itself is seldom the problem, the metal filings on it's magnet are.
