Originally Posted by MommaDorian
Originally Posted by patdesign
If your machine has auto tension controls it is a little harder to correct tension problems, but try making sure there are no pieces of thread stuck in the top tension discs, since that will hold the discs further apart which would tend to make the top tension too loose. I have a Brother Embroidery machine that does this and after a shop visit when the repairman showed me what the problem was, I just take mine apart and clean out the discs, and the problem disappears. The good news was that the dealer serviced it for free since the machine was only 6 months old the first time it happened. :D
What is the auto tension control?
A lot of machines adjust the tension automatically according to the weight thickness of the fabric being fed through the presser foot. Others ( a lot of the new ones) have the actual tension discs hidden behind white plastic and you just guide the thread through the slots and it automatically puts the thread in the right place. However sometimes when the thread breaks or if it is rough it deposits lint or tiny bits of thread in these discs that do not pass through. Thes little pieces of lint although they look insignificant, are enough to adjust the tension to a looser tension and that can cause problems such as you are experiencing. I had an old Singer 6268(1980's) that had an auto tension control, but still had some plus and minus settings that I could intervene to further adjust but otherwise it just automatically set the tension as I sewed. Boy do I wish I hadn't sold that machine! Any way I hope this helps explain. Don't remember did you mention the make and model fo your machine? :-)