You need to lower your door, completely closed, and then with the winding bars completely to take the spring tension totally off. Once you have no tension on that bar go to whichever side has the loose wire. On that pulley will be two square head screws. Loosen those two screws and rotate that pulley until there is no slack and that line. Then tighten those two bolts up. While you’re at it, you might as well check the other side to make sure it is adjusted to where there is just no slack in the line. after this you can start winding your springs to the proper amount of turns. Hopefully somewhere on the torsion bar, you’ll find a tag wired to it that tells you how many windings at spring should have. If not, you can call the manufacture and tell them what door you have and they will tell you how many spring windings it should have or you can count the. Amount of turns As you loosen the springs.
I no longer try to adjust the springs on my door! Scared me too bad the first time!
I was used a very large screwdriverand thought I had it held fimrly, only to let it get away and fling the screwdriver to stick in the sheetrock at the front of the garage!! Had there been anything or any person in the line of fire, they would have been seriously damaged!
I've found that one of the most likely times to get hurt is when you feel you know exactly what you are doing!
With sensing a very large lack of experience, I DO NOT recommend this project as a money saver. It can kill somebody!