The 930 is well worth a service. This model has an extra strong motor and the parts in the freearm is sturdily built. The stitch selection is veyr nice and it behaves impeccably when sorted out.
I would inspect for thread mess some where or part stuck like a broken needle or pin. It's hard to give anything but general advice; take the top off and the top of the free arm (remove needle and preser foot in advance). It's usually about cleaning and oiling, checking for thread mess either in the bobbin area or in the hand wheel. Inspect the white plastic gears as well. With good light and wiggeling the hand wheel as far as it will allow the problem should be detectable.
Last edited by Mickey2; 01-29-2017 at 07:54 AM.