You have two main options on this problem. First of all, there are companies that specialize in steering column repair. They work much cheaper than the dealer and will often come to you. There is a typical flat fee plus any additional parts.
If you can't locate one, call your auto insurance claim department and ask them who they use in your local area. These companies usually stay busy repairing theft and attempted theft damage to columns of all kinds. This ranges from $125 to $375 and may be well worth it considering the risk of working around the air bag.
Second option--do it yourself. First, purchase or rent a high quality wheel puller and turn signal plate puller. Get your handy dandy G.M. service manual and review the entire steering column section. Follow all precautions on disarming the air bag and keeping the clock spring in place.
When you get the wheel, clock spring, and upper horn plate off the column you will be able to see inside and maybe detect the problem. You will be looking for a loose screw or broken piece of plastic. It the turn signal assembly is broken, you will have to unplug down near the brake pedal and fish the whole thing out. Putting the new one in is a real trick. I used a hanger wire to guide the harness through the tight tilt section. The other problem will come in the plastic pieces just at the base and foward of the turn lever. Again, I can't stress enough how helpful the actual G.M. repair manual will be considering the exploded views of this area.
I have performed this job on my wife's 90. Her center column section was worn out causing the wheel to wiggle. I was able to get a center pin section from a Chrysler of all things and swap it with her unit. It took me four attempts. One of those attempts I did not set the high beam turn signal section back in correct and had the same problem you are having. I only figured it out after putting the whole thing back together.
Now that I think about it, it would have been well worth paying a pro to do this job. The good news is that it is fixed and working great.
Most of all, make sure you will not need the car for a few days and take your time. If you get in a hurry or force anything you will end up breaking some of the small plastic pieces or loosing the small parts. Don't get too frustrated if it takes you more than one try to get it right.
Good luck
