If the stainless ring spins on the bakelite part, remove the knob/shaft and hold it upright while carefully drizzling a little acetone in the center. Wipe off any that you get on the center dot using a cloth made damp (just damp, not dripping) with acetone. The acetone will swell the plastic inside and restore your knob. Method 2: set the knob upside down on a piece of wood, have your wife hold it for you and with a tiny screwdriver tap the back side of the stainless ring 3 or 4 times evenly spaced. This isn't my favorite fix, though. Carefully is the operative word here. You just want to make 3 or 4 small divots. If the entire knob is spinning on the shaft, just remove it, set it upside down and carefully put some JB Weld clear around where the shaft goes in the knob. Why clear? It tends to flow into cracks better, remains more flexible and to me seems a better bond between metal & plastic like materials.
As for replacing the headlight switch, Jerry is right. Remove the speedometer and you'll make the chore easier. Remove or slide back the gauge cluster and you'll make the chore a literal walk in the park. When you replace the speedometer, go to your ACE or True Value hardware store and buy 4 small wing nuts to replace the regular nuts. You may need to file the ends of them if they're too large, but you won't have to remove more than about 1/16" on each ear. If you ever have to remove the speedometer again, you'll spend a lot less time and you won't need to stand on your head.
