Have a pair of Blaupunkt speakers in the kickpanel area with a Europa II Stereo. One speaker had no sound, the other was OK. I looked at the speaker wiring and it looked like new...tight, clean connection.
The AM band on the radio was not working. I sent the radio to Becker for repair and told them to fix the AM, check the speaker channels, add levers for balance and tone (which were missing).
$175 and a two weeks later all was repaired and both speakers work. The speaker problem was in the radio unit not the speaker or the wiring.
Richard M, NYC
P.S. Funny part of the story: while the radio was out for rapair, I went to a car show. I carefully pasted a life size matte finish color photo of the radio over the empty hole. Many spectators and not one noticed it was a paper radio...didn't play well but it looked nice.