I don't have this particular machine but do have a Viking Platinum. Is this happening when you are piecing or FMQ? I'm guessing piecing. It sounds as though the tension is off - which is supposed to be automatic. If this is when you are piecing, start with a small scrap, in the middle of piece, then continue with your actual pieces to be sewn together. Check your manual to see which buttons need to be engaged for the auto tension to be working correctly. If this is going on when you are FMQ'ing, sorry I can't help you there. I don't do that.