I have had the exact same problem that you have had over and over and over again. To make matters worse this is my second Viking Husqvarna. I took my first one back to the store where my dear husband purchased it for Christmas for me.
Fortunately, I had my daughter with me, she was a communication major in college. She told me not to say a thing and I followed her advise. After about 1 hour of the owner of the store trying to prove that I had done something to the machine to cause the trouble. She proceed to have the same problem.
My daughter chimed in and asked her what she was going to do about the obviously flawed machine. Stating that her father was taken advantaged of, since he knew nothing about sewing machines. After my daughter's very logical arguments. The owner gave me a new sewing machine.
I was delighted beyond belief. When I got home and started to use the machine it worked perfectly. At last a sewing machine that worked. My delight did not last long. The owner of the store replaced my Viking with another Viking. After using it several times. The same thing started to happen. The design of the Viking sewing machine is wrong. The bobbin does not work properly. That is it!! Needless, to say I am now looking for another machine. The Viking has bobbed it last bobbin for me. Any sewing machine would be better than a Viking.
I have read this same complaints on several web sites. Everyone can't be wrong. Does anyone have any suggestions regarding a new reliable sewing machine.