Open your garage door fully and secure it in place. You need to raise the door as far up as possible and place C-clamps below the bottom rollers. Or you may place two locking pliers on each track under the bottom rollers. This safety measure is very important. If the door is not secured properly, it may roll down while you are working. So it is a smart idea to try tugging on the door to ensure the clamps are tight. Also, unplug the power cord to the door opener.
One more thing to do before you start working is to take a photo of the cables. Resist the temptation to skip this step, as most likely you won’t be able to remember how the cables were threaded and connected. Even if you will, it is still easier to work when you have a picture of how they were.
Is there a safety cable installed on you door? The purpose of the safety cable is to protect you in case the spring breaks. If your door has this type of cable, you need to remove it at the metal hanger not far from the end of the track. Do you see an eye bolt? Find a clamp on the cable. You may loosen it so as to give some slack in the cable. Warning: this step will allow the spring to fall, so hold on to the safety cable as you are loosening it.
Now the safety cable can be pulled out of the spring. Let it just hang off to the side. Then pull out the part of the extension spring that is attached to the eye bolt at the hanger.
Take a closer look at the track and the support in the back. If you notice that the angle iron is not in proper condition, replace it.
The second part of the spring is attached to the pulley with the help of a metal clevis. Remove the clevis from the pulley using wrenches. Pay attention to the state of the stationary pulleys. Are you sure they do not look worn and do not need replacement? When the springs break, pulleys are often not far behind. Wrap some tape around the pulley so that it does not move. Move the cable down and let it hang so that it cannot strike anything or get under your feet while you are working. Now you are ready to install the new kit of springs.