I cannot adjust the thread tension. The bobbin thread is too tight. Adjusting the screw on the bobbin doesn't help. Moving the dial on the top of the maching does not help. Is there a service manual for this machine or can anyone help?
Chris

Chris, May 2008

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

Hello Chris,
The bobbin tensions should be tight enough just to be able to pull the thread through with slight resistence, top tension should be between 4 and 6, make sure the presser foot is up when you thread the machine.

drivewithken@blueyonder.co.uk, May 2008