I have a single dial frister and rossman?

I have a single dial frister and rossman. The needles keep breaking by jamming in the parts of the bobbin casing that rotate around. Is this a timing problem? I was assuming it was a worn part, but reading other answers it may be timing is out. Would anyone have instructions on how to do this? Also the tension needs adjusting for the bobbin beyond the screw on the case - it just isn't enough to correct it..
Many thanks Trudy