6.1 It is time now to unwind the old spring that is not broken. A few warnings are in order. NEVER, NEVER, NEVER touch a set screw without first inserting a properly fitting bar into the winding cone! Also, do not use box or socket wrenches for the set screws. If the cone slips, the wrench could break your hand in 10 spots before unwinding completely. It's my guess that this is the number one cause of trips to the emergency room for inexperienced homeowners fixing or replacing their springs.
9.8 Twist the garage door shaft to tighten the cable on the drum. While twisting, vise grip the shaft as shown to keep the cable tight on the drum. The top of the vise grip should be tight against the garage header. This will keep the cable snug on the first drum while you install the cable on the other drum and position it in place. It also keeps the shaft from turning and the cables peeling off when you wind the springs. That one grip can save many hours of walking back and forth and having to level and re-level the garage door after winding the torsion springs.
11.2a Raise the garage door slowly. Check the door balance. If you have the correct springs the door should stay down when closed, half way when opened half way, and open when opened. If the door will drop to the floor by itself from the halfway point, add 1/4 turn of tension to each of the torsion springs. If the garage door won't stay on the floor, and if it pulls itself up when stopped halfway, close the door and remove 1/4 turn of tension from the springs.
If you have a garage door opener and you suspect a spring has broken, do not disconnect the opener from the door (by pulling the red emergency release handle) while the door is open. If you do, the door can come crashing down under its nearly full weight, with nothing to stop it. This is an extremely dangerous situation. It is never safe to leave the door open when a spring has broken because someone might try to close the door without realizing how heavy it is. Or, they might pull the emergency release handle on the opener. http://www.youtube.com/watch?feature=youtube_gdata&v=Z_eZc-kh40c
Refrain from parking your car in the garage until the garage door is repaired. Additionally, try not to open and close the door while it’s in this condition. With that amount of possible force coming from the springs or cables, they could potentially damage your vehicle or other property in the garage as well as cause serious injury. It’s especially important that you and your family stay away from these cables or springs until everything is repaired.