I would use what your manual or DVD is telling you to. The expense to fix your machine would not be worth trying other bobbins. A good rule is if the machine comes with plastic bobbins, use only plastic bobbins and the size they recommend. Vikings usually have there own special bobbins. I have 2 vikings and the bobbins are not interchangeable. Many times the feet for the vikings don't work on other vikings either.
I also have a Brother machine and it takes its own # bobbin also.
Suzy