I think I can; the bobbin thread is being dragged up and if you look very closely you will detect the white tread perhaps only as straight line in the middle of all the zigzags (no zigzag at all on the upper thread). It's cause by way to tight upper tension, or little to no bobbin tension, or a combianation. You can get similar problems if you have too thick thread for the needle eye too. Have you double and trippled checked threading, cleaned under the needle plate and bobbin case?