A good-quality garage door opener may go for many years before it needs replacing, but even the best brand of opener will eventually wear out; the heavier the door and the more often you use the unit, the sooner you'll need a new one. A garage door opener doesn't need to fail completely to need replacing; note a few things you might check when the door doesn't open and close as it should, and, if these are not the issue, it's time to consider an entirely new opener altogether.

The door goes up and down rather than closes

If you try to close the garage door and it goes down partway but then opens again, check the tracks for any obstruction. Also, note the eyes in the door tracks, as these send a clear beam of light between them to ensure there is nothing blocking the door's path; if there is something on one of the eyes, or even if it gets especially dusty or greasy, this can cause the door to stop closing. The tracks should also be straight and even, as a bent track can send the door back upwards. If none of these are the issues, the opener probably has faulty wiring or sensors, and it needs replacing.

Door doesn't work at all

Note if you can hear a hum when you try to open or close the door; if not, the motor of the opener is not working, and it needs to be replaced. Also, note if you can pull on the garage door to close it; don't pull too hard as you're testing to see if a chain or spring is broken. If it is, the door can come down very quickly. If it seems to move easily with no resistance, the chain or spring needs replacing and not the opener.

The door slams shut

A spring or chain might be broken, as mentioned above. However, if the springs and chains are fine, the opener may need to be replaced. It has sensors that tell it how far to release the door so that it closes safely and that also control the speed of the door as it descends. Once these sensors are broken or malfunctioning, the door is no longer controlled by the opener and may simply slide down the tracks, slamming onto the ground. This is very unsafe for you and may also cause the chains or springs to break from the impact, so have the opener replaced as soon as this begins happening.