I have been trying for over a month off and on to get the tension right on my Brother 1500S. It is a wonderful machine and it normally sews beautifully, but I think the tension is off and nothing I have tried fixes it. Here's what it's doing: When I sew a seam, the top seam is perfect, but underneath, you can see the barest hint of the top thread, so the tension is not quite balanced. The stitches do not pull out, nor are they puckered, but seeing the upper thread on the bottom is driving me crazy. I know it is not supposed to look like that.

I have set the upper tension in about the middle (I have tried all settings of this.) The machine is clean from top to bottom, I have tried various brands of thread, using the same thread in the top and bottom and have changed the needle. I have threaded and rethreaded according to the book and I always thread the machine with the foot in the up position.

I really hate to have to take this machine to a dealer for servicing just because I cannot set the tension right. The machine is fairly new and is cleaned often and the needle is frequently changed. I have read before of others who struggled with machine tension and I have tried to do everything suggested. Based on what I have described, does anyone know exactly what I am doing wrong and how to fix it? I welcome anyone's ideas or suggestions.