If it's the bobbin itself turning slowly in it's case I would suggest a good wipe of the bobbin case, and check if there's something up with the bobbin, try a different one. I would check the tension spring for any bits of thread caught some where, as well as race/hook/feed dog area. Don't fill the bobbin too much either. When the bobbin thread is drawn up the needle plate and you pull it a bit, the bobbin should turn freely. If it has been standing since 2013 I guess in only needs to be oiled and used again. If you have the version with belt driven motor you can with advantage use oil on all parts (except motor) but remember to oil frequently. If you have the potted motor, use grease on the spiral gear on top near the hand wheel.
Last edited by Mickey2; 04-09-2016 at 11:42 AM.