how do I know which way to adjust my bobbin?

Hello Jennifer,
To tighten the bobbin tension turn the screw clockwise but very gently, you should just about be able to pull the thread through, top tension somewhere between 4 and 6 should be right depending on the thread, if you have the black bobbin case known as an apollo you will have to be very careful what thread you use, don't use unmercerised thread, make sure you have the right size needle for the thread, any problems you can e-mail me drivewithken@blueyonder.co.uk
I can give you addresses for manuals if you need one.
Ken

drivewithken@blueyonder.co.uk
October 2007