Having problems with my tension...I have tried every possible adjustment position....it worked perfect for the main part of my quilt, then when I switched the color thread and started working on the border the back part has these loops coming through. I have tried it out on all the different positions. Then when practicing I found that it worked fine on the one with the main fabric (which is also my trial piece) but when I switch back to my border it doesn't work again. any suggestions?