I am just in the middle of a heating problem with my W123. The console lights have all failed over the years. I was studying the setup there and remembered what an electric tech told me years ago. "If there are things you don't understand, check the ground first". So I ran an ohmmeter on those ground wires that go into each of the bulbs. None of them were working. I located the ground conection back in there and tightened that screw and now they all light up. On this one the ground wires are all small black wires with bare metal points at the ends. Just check a few of those. Maybe....