Tumbler likely worn out. On 1994 and older ("old" interior and column) you can replace it pretty easily. You'll need to borrow/rent a steering wheel puller tool, and lock ring depressor tool. Pull the wheel, depress lock ring, pick to get the clip, release lock ring (careful; it's got a spring behind it), 1 screw on the turn signal lever, couple or 3 screws on the turn signal cancelling cam, move that aside, there's a little slip-in set of contacts for the "key in ignition" warning chime, then a torx screw and you can pull the tumbler.
Sounds like a lot but it's not. There's probably plenty of videos on youtube about it that you might watch first as I just did that from memory off the top of my head and it's been several years since I've done one.
Richard