I have the same radio on my 1987 560SL but would only be guessing that a connector on the back of the radio may have come loose. Do your self a favor and call Becker of North America. Becker handles the antennas as well. They are very telephone friendly and have always been willing to discuss vintage Mercedes Becker problems. Here is there website address:

http://www.beckerautosound.com/

There phone numbers are: (201) 327-3434 (888) 423-3537


Good luck!

J. P. Mose