tension - National/Cromwell machine
 

I was recently gifted with a Cromwell Machine in a beautiful table. I found out some information about it - it was made by national before 1950. My husband fixed all the electric parts. I figured out how to thread the machine, wound a bobbin and tried sewing on some charm squares. After some adjustments I think I have the top thread just about right, but I have loops on the bottom. I'm used to sewing on a Viking where I don't ever have to adjust or change the tension, so I'm at a loss here. Do I tighten the screw on the bobbin case? I've tightened it some, but if I go too tight, the thread won't slip into the groove. Any suggestions?
Thanks,
Susan in NE PA

Loops on the bottom usually means the top tension is too loose. Try turning the dial a little bit to see if that helps. https://www.youtube.com/watch?v=mWajfDxQQwo The video may help you understand how to adjust tension.