In most cases, only one spring breaks or wears out at a time, and you can get away with replacing just the failed spring. But this is a little like replacing old car tires one at a time. You'll get the best performance if all the springs are new and have the same strength. Extension springs are replaced individually, making it more tempting to replace just one. With torsion springs, you have to disassemble everything to replace either spring, so it makes sense to swap out both springs during the repair.
The tricky parts of the job involve you carrying the tension of the spring. Replacing a spring requires that you first unwind the spring to relieve the tension, then wind it back up and secure it while it's under tension. Winding bars are used for all winding and unwinding actions—don't try to save a few bucks by substituting long screwdrivers or pieces of rebar for the real winding bars. Substitute tools are much more likely to slip, or they may bend or break under the load of the spring. 

Jerrod the technician had answers to all my questions. He was very knowledgeable and very patiently explained what was going on with my garage door and the opener. I would definitely recommend A1 garage door service to friends and family. I was given options to either repair the door or replace it. I will get the door replaced when it gets non-functional from A1 garage door service.
It’s difficult to say how often the springs will need to be replaced since it’s different for everyone. It depends on how often you use your garage door, how cold and long your winters are, how well you maintain your springs and many other factors. The best rule of the thumb is to check your springs regularly for signs of wear and damage and to replace them when they begin to appear tired.
So your garage door is acting up, but you aren’t sure what the problem is. Maybe the door spring is one possible culprit, but you’re not sure if that’s actually the problem or if it’s something else. In this quick list, we’ll go through the most common broken garage door spring symptoms. If your garage door is exhibiting one or a few of these symptoms, there’s a good chance it’s broken and needs replacing.
If your garage door goes up and down in a jerky motion, you might have one broken spring on a two spring system. Some garage door openers are strong enough to lift a door with only one good spring. The “herky jerky” motion is especially common with garage doors equipped with extension springs. It might be something as simple as lubricating your garage door pulleys, hinges, and rollers. When in doubt or if something doesn’t feel right about your door, call a service company to have it serviced.
Extension springs last 15,000 cycles. Every time the door goes up and down is one cycle. On average extension springs will last 7 to 12 years. For most people, you know you need to replace your extension springs because it snaps. Sometimes, however, when extension springs get older, they can lose their tension and the spring becomes elongated. This is rare but it does still happen. Basically, the coils are fatigued and when the door is up you can see gaps where the spring is not relaxing properly. When this happens, the spring is useless. It is best to replace the springs at this point rather than overworking the opener which will cause it to last a shorter life.

The winding and unwinding is done at a metal fitting, called a winding cone, attached to the outside end of the spring. You stick a winding bar into one of the four holes in the cone and use the bar as a lever to turn the cone. Once you've completed a quarter turn, insert the other bar into a different hole in the cone and let the bar lever against the closed garage door to hold the spring tension. This allows you to move the original bar to repeat the process, alternating the bars with each quarter-turn. It takes about 30 quarter-turns to fully tension a standard torsion spring. https://youtube.com/e/Z_eZc-kh40c
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