Grab one out of a pick and pull after establishing it is good. May require you to take a small twelve volt battery to test it. German car radios were never my favorite playground when I repaired electronics proffessionally.

European electronics were always a little strange compared to north american products. The oriental stuff I found closer to ours. For example one of europes leading electronic manufacturers phillips wanted to stay in the north american market so bad. They paid my firm a lot of money to deal with their products. They were such a nightmare that rather than repair we developed running modifications for their product. There reliability was still horrible.

Or advertise on our parts wanted site. Quite a few members have pulled good becker units to replace them with modern radios. They should be willing to sell them cheap just to eliminate storing something they will in all probability never use again.

Do not send the radio out to becker for reconditioning. It will in comparison cost an arm and a leg. Or if the radio appearance is not too important to you a lot of aftermarket units preform much better than your radio ever did or will .Some decent replacement units are prettty reasonable today as well. Your call.

If I was not retired and caught up with everything. I would start to re engineer changes for the problamatic newer mercedes. There has to be a gold mine there. I have no ideal why their product degenerated so badly. Other than the cars where not considered to be a major profit centre of their empire. Perhaps their egos did them in but a lot of their electronics where and probably remain junk.

Tired old european speakers are not the best either remember. The speaker cones where not even average climate resistant and will decompose with time alone. This did apply to the majority of other manufactures speakers back when these were made as well.