I had a similar problem and Rick on this site was kind enough to give me some advice. Lay the machine on its side so you can just place the bobbin mechanism pieces into the bobbin shuttle area. Put the small half moon shaped piece in first, then lay the round piece in with the little notch at the bottom. Loosen the screws that hold the arms that hold the bobbin shuttle in and position them over the small 'bumps' on the bobbin housing. Once you have the arms in position, tighten till firm (not enough to strip the screws) and then set the machine upright and insert the bobbin case with thread.

I really hope I've helped you like Rick did for me.

Anna