Hello Jan,
Check all the basics to make sure you have not missed anything, make sure the presser foot is up when threading, top tension about 4 or 5, bottom tension tight enough so you can only just pull the thread through with some resistence, if it is too tight slacken the screw on the bobbin anti clockwise about a quarter of a turn at a time and test.
drivewithken at blueyonder dot co dot uk, October 2009
