I'm going out on a limb and assume yours is like all the GM products I've ever worked on.

Before doing this, consider the possibility that the problem might also be with the switch located towards the bottom of the column, the rod that pushes on it (when you turn the key), or just a worn key.

I used to have a site bookmarked with these instructions including pictures. That one's gone but these instructions (link) are good. The last column I did was an '86 so it didn't have the air bag. These instructions tell how to do the whole column. You won't get that far into it so it's not near as bad as it seems. Special tools you'll need are a steering wheel puller, and a lock plate remover. Cheep ones good enough for you are available at Harbor Freight. Basically you'll disconnect the battery. Remove whatever is in front of the center of your steering wheel. Remove the clip and nut holding the steering wheel on. Remove the steering wheel using the puller. Compress the spring using the lock plate remover and remove the snap ring. Remove the tool, lock plate, horn button switch, and spring. You now may or may not be able to remove the lock cylinder at this point...don't remember. If you can see the cap screw that holds the lock cylinder in, remove it and the lock cylinder. If the turn signal switch is in the way, unplug the wires at the base of the steering column, remove the 4 screws that hold the turn signal switch in, and carefully pull it up enough to get to that cap screw I already mentioned. If your vehicle is equipped with VATS, you'll have to get a cylinder with the VATS number that matches your car. If so equipped, you'll have to unplug that plug at the base of the column too, tape something to the end of that wire to pull through the column as you remove the lock cylinder so you can easily pull the new wire back through the same path. Reverse that process to reassemble. On a scale of 1-10, I'd rate the difficulty level at about a 2 1/2 for this repair.

jmo

Here is a link that might be useful: gm steering column repair

How about shooting some powdered graphite into the keyway to see if that helps? You can get a squeeze tube at any locksmith shop or in the key dept at HOme Depot...about $2.98

Thanks guys for the replies. I think I will try the graphite first.....Jim

Would the same instructions apply to a 2000 Chev 2500 pickup that does not have an airbag?.....Jim

I had another page bookmarked that still exists. Can't swear yours is exactly like this. GM has used this basic design from the 70's to this '92 pictured at least though. For the lock cylinder replacement, you just have to go down as far as step 17 if you decide that's what you need to do.

Here is a link that might be useful: pictures

Gary, Thanks for the pics.