Although I have been known to use the wrong bobbin (see my last post over here
World's Best Sewing Machine ) in this case I was using 66 bobbins. I tried the top tension at everything 8 and under on the dial. The last picture is my "test kit" for use on machines after I clean them up. The needles are brand new, but I can switch anyway. I will try testing as you suggest, and I think I will also switch to vintage 66 bobbins, can't hurt.