Tip on bobbins--I always take mine apart and then screw them back together tight but not too tight. This really helps with newly purchased bobbins whether they be Singer or generics. I always do a 'test run' on new ones--meaning I only wind a bit of thread on them to see if they sew well. Be sure edges of bobbins are smooth--you can use an emery board to smooth out any rough spots. Hope this helps .