Originally Posted by
Dolphyngyrl
could it be the bobbin is the wrong bobbin for the machine,
This was my first thought. Several years ago, my friend inherited her Mom's Bernina 930 and it was "broke". She took it to the dealer and found out her Mom had been using class 15 bobbins not Bernina bobbins. She bought some Bernina bobbins and after servicing the machine just purred. She is still using it.