I have a problem with my 1984 190E. Twice in the past my dash lights have quit working, but came back on. I removed the panel to repair the speedo and the dash lights now wont work. I have rechecked all the wires but they still don't work. The rheostat does work with the heater controls and the transmission. Any ideas where to start. I did a check on the forum but couldn't find this problem. Help!!