Thanks for responding. By now we have figured out that my sister in Germany had forgotten to do a certain step you have to do when putting the bobbin thread in. She was to proud to ask her dealer and she is pretty new to the machine. :-) I joined a Yahoo group for her and figured out by reading their posts what she had forgotten to do.
There should be no need to adjust the bobbin tension. But if you wish to fiddle around with it - I would only do that as a last resort - you have to take the black bobbin-holder out and adjust the screw on its side. Be careful only to turn a quarter of a turn at a time and best mark the initial position as well.[/quote]