(1)does the downloaded manual say if the bobbin should be metal or plastic?
(2) Is the bobbin thread suppose to go to the right or left? (right => when the flat side of the bobbin faces you, the thread hangs down on the right side and bobbin plus thread looks like the number 9. Left=> when the flat side of the bobbin faces you, the thread hangs on the left side).
I teach sewing to kids and these are the two major problems in every class.