I have to admit... I have to use my backup machine now because I seem to have pulled my shank out of alignment and it is hitting the bobbin..Tried changing needles and turning off and on, but OOPS... maybe you shouldn't try this at home....LOL... I have more than one backup machine, all just newly serviced, except the one I just messed up. They are 24 years old, so I am not too upset as long as one still works.... I probably should have used an 18 needle and I was using a 14 or 16 and going through clear plastic-heavy woven-and folded over vinyl more than one layer of each...so amazing anyway!