I have a little blue thing called a "Tension King" that I bougt years ago. Using it really helped me. If things go off I use it. It has me thread the machine above and then pull on the barrel until the plunger comes out to the line "A" adjusting the tension until it is in the right mark, then do the same with the bobbin thread with the plunger pulling out to the mark "B". I haven't seen one recently but I would hope they are still out there.