1. Track-and-rollers Most homes use overhead doors for the garage entry. Those that use a track-and-roller system are the most commonly installed doors today.

2. How springs work Overhead doors are heavy, whether they are made of decorative wood panels or insulated metal. The average 16-by-7-foot door weighs around 280 pounds. The springs are an assist system that counterbalances the weight of the door with the energy stored in the springs to allow the user to open the door with little effort.

3. Types of springs There usually are two springs for the average residential garage door and, depending on the size and weight of the door, there are two types of springs to counter the weight of the door. Torsion springs are found on a long metal bar above the door; as the door is closed, the springs wind tightly, storing energy in the metal coil. As the door is opened, the springs unwind, releasing enough energy to aid in lifting the heavy door. Lighter-weight and smaller doors use tension springs, which are located on either side of the door's overhead track. When the door is closed, the tension springs are stretched, storing energy in the metal coils. As the door opens, the springs relax, releasing the stored energy to help lift the door.

4. Don't skimp When replacing tension springs, both of the springs should be replaced and matched because the older, unbroken spring will have lost some of its tension from years of use. Replacing both springs helps to balance the door so that it opens smoothly and with equal force being applied to each side of the door.

5. How to adjust Once installed, tension springs can be adjusted. Measure the length of each cable, and secure them to the door's track while the door is open and the springs are relaxed.

6. Safety first It is important to install a second cable inside the spring in case the spring comes loose or breaks.

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7. Hire a pro A word of caution for the DIYer: Torsion springs should be replaced by a skilled installer. Torsion springs have so much stored energy that they can cause serious injury or even death if mishandled. There have been situations where a torsion spring's mounting system had broken, releasing both of the torsion springs, which put a large hole in the garage ceiling.

8. Getting help You can find the average weight of your garage door by visiting garagedoorpartsllc.com /weight-calculator.html. With this information, if you decide to do the repairs yourself, take the old or broken spring to your home store or garage-door dealer for help in finding the right parts.