Most repo light switch rods are slightly thicker than originals, so that little brass collar that fits so nicely on original rods will not usually fit on new ones. I have found that if I just take 80 grit sandpaper and sand all round the area on the aluminum light switch rod where comes into contact against the steering shaft and steering wheel hub, the tightness is eased and the switch won't turn when the steering wheel does. Finish with 220, then 400 grit or finer. You may also want to take a rattail file and clean up the last 1/2" inside of the steering shaft. It can get distorted when removing the steering wheel or from heavy-handed hammer use with a "knocker". If you can move the rod up and down in the area contacting the shaft and wheel hub without it catching (before putting on the steering wheel), you should be o.k. Be sure to put some oil or grease on the last inch or two of the steering shaft.
Marshall