Weird light bulb problem 1991 300d

[jbach36]

When I turn on my lights, I sometimes get the dashboard light that tells me one of my lights is out.

It's usually the right rear side marker, or tail bulb. I might touch them to turn them and they'll come back on, or maybe not. I've replaced them many times over, and....same problem. This has happened for years and it only happens occasionally.

The other day, my dashboard light is now on all the time when my lights are on. It's now the left rear side marker bulb. It won't come on unless the car is off.

Any suggestion?

jeff 1991 300d 202k