Tailiight out, get low voltage reading?

[JBoggs]

I have one tailight out on my 83 380sl. Figured it was just a bulb but replacing the bulb didn't help. Tried the bulb in the other side and it works fine. Took a voltage reading from both sides and the good side reads 12v + the bad side about 1.3 volts. All the connections appear good. The head lights work fine and no fuse are out. Oh, by the way the dashboard and panel lights are also out but I think I know why.

Any troubleshooting that I can do to see why the tailight is out?

Thanks.

J. Boggs