Nate was very courteous and professional and called to let me know that he was about 30 minutes from my house. I had purchased a new Sears garage door opener, but when Nate arrived at my home, he inspected the existing unit and told me that it was still in good shape except for a worn out part. Nate procured the new part and brought it to my home this morning. The unit was repaired in about 10 minutes! The existing unit was just over five years old, so I'm glad I will get some more use out of it. http://youtube.com/v/Z_eZc-kh40c?version=3
On one-piece doors with side springs, you open the door to relieve the spring tension, and simply swap out the springs on the opener-arm mechanism; there are no cables or pulleys to deal with, and the springs have internal safety rods. Some doors have tensioners that maintain moderate tension when the door is open all the way, and on these you'll have to loosen the tensioner in order to remove the spring.
Just like on a bike sprocket, your cables can sometimes become disengaged. Oftentimes, when a torsion spring breaks, the garage door cable will snap as a result. Sometimes, the cable will cause damage to a vehicle or wall, and if a person happens to be in the way of the cable it can cause serious harm. If you cables have snapped, you should call a professional to help you. See the video above.
10.7 Continue tapping until the cone moves out to the mark on the shaft. Continue holding the bar off the garage door and pulling back toward the center of the door. If the cone slips away from the mark, repeat this step. Keep an eye on the tape to make sure the bar doesn't slip out of the cone. If it does start to slip, rest the bar against the top of the garage door, insert a bar in the next hole and turn the cone up enough to make it possible for you to push the marked bar back into place.
No matter what kind of door you are installing, be very careful. The instructions that follow are merely guidelines. You should read your garage door manufacturer's instructions and owner's manual very carefully before attempting either type of installation. And if you're a do-it-yourself greenhorn, skip this project and hire an experienced professional. It may be more expensive, but garage door installation is on the higher scale of DIY difficulty.