I don't have a stitch regular and I don't have a viking machine on my Grace frame. But I had the same problem. It was me. I realized that if I started moving faster then machine was sewing I would have skipped stiches. That will also cause the thread problem too. It dose take some getting use too. Mke sure your guilt is taunt not tight on your frame. Also that your needle is sharp. I made a crib size sandwhich just to practice on till I got the hang of it. I also put it on frame before I start quilting a new project just to warm up. Espically if its been awhile since I last used frame. Hope this helps
Oh I have a Juki TL 98 QE on a Grace sturdy Lite