When ever I get around to a new machine, I clean, oil check for burrs and take apart the bobbin area, clean, adjust and put back then clean up the bobbin case, including behind the spring - then adjust. Then I take the tension apart, clean and rebuild. Usually that takes care of any adjustments. Occasionally something else is the problem - but you do have to have everything put back correctly. My sister had a Singer 503 tension she took apart a bunch of times because the tension was driving her crazy. She actually had the thing put together correct. Finally I told her to try a tension from a different machine. It did the same crazy thing. So she started looking at everything carefully. There were burrs on the thread guides. I have seen dried up oil inside a tension make so much drag that the tension would not work correctly. If you are uncomfortable doing the servicing yourself take it somewhere and have it done - make sure it is taken apart and put back together - just flossing between the disks may not take care of some issues.
Last edited by miriam; 06-02-2014 at 05:21 PM.