To make it easy, test sew with Gütermann sew-all weight polyester, or at least a good quality thread. If you plan to sew with top stitch thread weight, use that. Use two layers of woven shirt weight or quilt weight cotton.
Ceck top tensioner; thread up the machine, when you pull the thread backwards do you feel gradual increase in tension when turning the dial from 0 to 9? 0 should be very loose, 9 should have a firm grip. Tension should release when presser bar lever is up, and there should be pressure on the tension disks when it's down. For the average sew-all thread tension should in theory be some where between 4-5 on the upper tension dial. When the top tensioner is correctly assembled it turns easily from about 0-9, or 0-0 it doesn't matter if the numbers are slighly off the mark.
Bobbin case tension is a bit more of a test and trial situation. Do a simple drop test with the bobbin case. I think tension should be around 1 oz (a bag of rice or beans can be made and used as a drop weight). Set the top tension dial some where between 4-5 and fine tune bobbin tension from there. (In other words test sewing).
Make sure you match thread weight, fabric weight and needle size suitably. If you up the thread weight up the needle size. Go for needle size #18-19 on heavier fabrics. I guess you don't hem jeans or sew flat felled seams too often on a Featherweight. Basic shirt or quilt weight cotton is usually sewn with #10-14.
Neelde in flat side to the left and it threads from right to left. MAke sure the bobbin goes in the correct way.
Last edited by Mickey2; 09-14-2018 at 01:37 PM.