Made some progress since posting my symptoms. I cleaned and roughed up the switch contact area behind the dash. I now have a dome light, at-least at times. If I turn the knob, the light comes on and gets brighter as you turn like the dash lights. No dome light if the park lights or head/tail lights are turned on. I'm thinking the switch may not be making good contact to ground as it travels over the bump. Going to try a spare switch. Any comments or suggestions are certainly welcome.
