Welcome to the Board! There are two springs, the upper thread tension spring, the spring with the loop, and the bee hive spring which puts tension on the discs via the thumb nut and controls how easily thread is pulled through. My experience has been that not enough tension on the discs lets too much thread through creating the bird's nest on the underside of the fabric. I have also run into problems having the upper thread tension spring either too tight in the housing, where the loop won't pull beneath the thread guide to the left, or too loose and it won't pull back on the thread properly.
You should be able to move, with your finger, the upper thread tension spring loop freely through the arc and it should bounce right back to the top of the arc, and the loop should be positioned above the thread guide to the left, at least that's how I get them to work.