I picked up my machine from the repair shop and was looking forward to some lovely smooth sewing. I was disappointed! The repairman had set the tension correctly. The top tension was set to the big red line on the dial at 4 (I usually have it at 1) and the bobbin tension was tightened to match the top. I don't know if there is something wrong with my machine but if you set the tension where it's meant to be, you can hardly pull the thread through the needle or the bobbin. So I adjusted the bobbin tension so that bobbin 'walks', ie when you dangle the bobbin by the thread, the thread slips through slowly. Then I adjusted the top tension to suit.
Another test on my free motion quilting scrap was still like trying to sew through treacle. My lovely fine 60/8 needle had been replaced by something that could sew several layers of denim! A change of needle fixed the treacle problem and I could at last get on with the dragonfly. I love the pebbles on the black fabric.