@bigobassman, Thank you for the welcome. I think I will look for someone to have a look at the speakers, a friend of mine already told me that the wiring is okay so far.
@stanner, thank you too. I am located in Germany. Will be lucky to find anybody at all around here who can repair speakers I guess.
Could someone tell me anything about the original speakers themselfes? Besides the 16ohms, 50watts there seems to be no additional information available like the manufacturer, model...
Regards, Florian