Sorry I can't post a picture, I have no idea how to do it. I will try to describe it better though. When I sew a 1/4 " seam joining two square together, if one is a darker fabric the needle will sometimes pull fibers up to the top of the lighter fabric. The seam is okay but when you look at it you can see the darker fibers on top. I know this sounds like a tension issue but I have played with the tension and it still does it.