Yeah, all of my tilt wheel Buick's has had this problem. It is fixable, there are three external Torx bolts below the turn signal switch(only two are accessible without tearing the top half of the columns down) I have successfully removed those two bolts and placed Loctite on them and reinstalled, they never came back loose again. You will have to pull the steering wheel, remove the snap ring retaining the lock plate assembly and gently pull the turn signal switch and harness up (just a little) through the column to gain access to those two bolts tighten and your done.
