There should be a small brass bushing at the top of the light rod. If that is missing it can cause your problem.
Bratton’s has them. This is from their website: “ This bushing slides up the horn rod to the top under the switch handle disc. This keeps the rod centered in the steering wheel. If this is missing, the horn rod drops to the bottom of the steering wheel hub, resulting in the lights turning on and off as you turn the steering wheel.”
https://www.brattons.com/media/catal...6/5/0/5050.jpg