I have been practing away on my Queen Quilter 18 the past few days and trying many different kinds of threads and keeping having the same issue arise no matter what I do.....in the bottom of the stitch where the knot should be it keeps showing the bobbin thread just slightly on the top of my quilts. I have adjusted the top tension numerous times even a whole turn at a time and it still does not seem to help the issue. Then at times it will it not be an issue but maybe for a couple of inches or so them right back to showing the bobbin thread. Any one have any suggestions???