I am not familiar with your make of machine, but in your tool box there should be a small screw driver. In the foot plate where your needle goes into to get the bobbin thread there are a couple of screws. Undo those and take the foot plate off and have a look inside. There could be fluff or thread inside causing loss of freedom for the bobbin to turn. or maybe a small fragment of your broken needles. Get the brush supplied in the tool box and give it a clean as best you can. My bobbin housing comes right out and I can clean under neath it. Be careful when replacing the bobbin housing, there is a way to do it so it fits snugly. Before reassembling completely, test things are OK by gently turning the fly wheel of the machine and see what happens. Then try it with a needle in place and again gently turn the fly wheel and listen and look at what is happening. I agree with "Just me" in that you should use recommended bobbins for your different makes of machine. I hope this helps, all I can say is if you are brave enough to have a look go ahead, but if you are too nervous, it's a trip to your local machine shop I guess. Good luck. Let us know how you get on.