Have you tried re-threading everything? When is the last time you changed the needle, and have you tried a different bobbin?
Susan

Along with what Susan said,when was the last time you cleaned the machine?? Perhaps you have a lint buildup n the bobbin area!!

I would start over,clean the machine,re-thread it,change the needle,re thread or change the bobbin and check your tensions.Most of the time it's something simple that we just overlooked.Good luck and let us know if you solve your problem.
Kathi

Yep I did all the things mentioned above. I have beening sewing for years and this is just giving me fits! It seems like a simple tension problem but I just can't get it correct. I love my viking and it has been such a good machine for the last 22 years. Nothing fancy just a great machine. It only has been serviced once, and that was just last year. He said it had many more years left in it, when I picked it up.

I just ordered genuine bobbins today, I will see if that helps. Luckily I have a back up machine I bought at a garage sale last summer. New in box singer, made in 1989 for $10.00!!
Thank you
Judy

Just reviewed the question, and possibly have an answer for the bobbin. There is a small screw on the outside of the bobbin that controls the tension of the thread on the bobbin. If you tighten it just the smallest amt. and see if the stitches are get closer. Do this until it gets back to normal. Sometimes the older machines get this problem due to many pulls on the thread on the bobbin. Maybe this will help. Good Luck

Hollysgamma,
I tried that too, no luck. I guess if the new bobbins don't work it will have be checked by the doctor! LOL
Judy

The way the bobbin thread unwinds matters. Check your manual & make sure you have that correct.

The bobbin is correctly inserted, I am just stumped. I have been sewing 30 years plus and never had such a problem. I guess it goes to the doctor after the holidays! Luckily I bought a back up machine last year.
Thanks everyone
Judy

I saw one of the TV sewing hosts show how to test if the bobbin tension is adjusted properly. Perhaps you have seen it too. Pick up the thread and allow the thread to lift the bobbin case into the air. If it hold tight, the tension is correct. If more thread slips from the case, it is too loose. I hope you can visualize this test. (of course, it could also be too tight in some situations.)

This can also happen when the needle is in backwards. Colleen