Do you have the original bobbin model that fits the Bernina 801S or do you have any bobbin? There could be the problem.
Do you put the spool of thread in the right way?
If you pull the thread from the bobbin by hand, does the thread come out easily (I mean, do you have the tension you wish to have) if yes, the problem may be when you put the bobbin in the machine.
If the thread comes out too tight, take the small scew off completely and check for anything that can block the mechanism (it does not take much...dust can prevent mechanism from working properly). Clean it up, and put the screw back on ( I would even suggest to put a drop of oil on a piece of tissu and clean the threads of the screw) and try again to pull the thread by hand.
If it does not solve the problem, check the small plate on the bobbin that gives the thread the tension, anything wrong with it?
jolydalie@hotmail.com
November 2008