[El Sol Infinito]

Thought I'd run this one by you all:
Last week, my taillights stopped working on my '64 after a period of intermittant operation (one side would work then go out, etc.). The brake lights and the turn signals work fine. The headlights work fine as far as I can tell. Since the taillights all share the same housing and bulbs with the turn signals and brakes, I doubt its a ground issue at the back of the car. Another thing that may be unrelated is that the interior lights and dash lights have not worked since I've owned the car (1+ month). Know where I'm going with this? I'm thinking (hoping) at this point its the dimmer rheostat. Any recommendations? Anywhere else I should start looking?
Any advice will be very much appreciated.
Bob