I have quilted several quilts now and on three of these quilts I continuously had problems with tension. After running several bobbins on the same quilt top, those bobbins ran out and I had to wind more. This one bobbin I have does not wind all the way and will start and stop winding. Then using this bobbin with the very same thread, pattern, and cloth it creates looseness in spots on the top and loop-de-loops on the back in spots. Any you longarmers had a warped m class bobbin? I suppose it can happen as it is twice the size of a regular bobbin right?