"Open sesame!" Garage door openers are the unsung heroes of modern life. Without them we would have to actually get out of the car to open the door. With them we simply push a button and drive right in--unless the opener doesn't work (or the garage is full of broken stuff). It's a good thing that garage door openers are relatively low maintenance and easy to fix.

How Does It Work?

Components of a typical garage door opening system.

A garage door opener is an electric motor appliance that opens a garage door at the push of a button. The button can be one that's wired into the household electrical circuit or one that's on a battery-powered remote-control unit usually carried in a car. Most garage door systems have both. The button sends an infrared or radio signal to the control unit that, in turn, activates an electric motor with a track-and-pulley system that moves the door. Most garage door opener units also have a light that goes on automatically and shuts off after a pre-set interval.

What Can Go Wrong?

The opener may not respond when the remote or wall button is pushed. The opener may raise the door but not close it. The opener may run but not open the door. The opener may operate without a command. The door may not open or close completely. The door may reverse when closing. The opener may have to work too hard. Because garage door openers are little more than a motor and electronic controls, most of the service you can perform includes replacing batteries, testing the motor or controls, or lubricating and aligning mechanisms.

Fix-It Tip

At least once a year, test and replace batteries in the remote controllers.

How Can I Identify the Problem?

If the power goes out, you still can open your garage door by pulling the release rope and manually lifting the door.

If the door opener doesn't respond, make sure the cord is securely plugged into a properly operating electrical receptacle . Wait 15 minutes for a motor overheated by a binding door and try to open it again. As needed, test the motor .

If the door raises but won't close the door, make sure the beam sensor is plugged in and properly aligned according to the owner's manual directions.

If the opener operates by remote, but won't operate by the hard-wired button, look for loose connections or damaged wires. Test for continuity or a short or call for an electrician.

If the remote control does not work, check its battery (see the Household Battery Fix-It Guide or the Button Battery Fix-it Guide) for sufficient power. Also make sure the antenna is outside the opener housing.

If the opener runs but doesn't open the door, look for wear of the worm gear or chain-drive sprocket; if needed, have it professionally serviced. Pull the disengage cord to reset the catch and reactivate the opener. Replace a broken chain or worn gears.

Fix-It Tip

Don't take your garage door opener for granted. Once a season, test the unit to make sure it opens and closes smoothly and that safety features (automatic reversing) work as described in the owner's manual. At the same time, inspect the door, tracks, and the opener chain or drive to make sure grime or debris won't soon stop operation. A 10-minute inspection can give you confidence--and reduce potential problems.

If the opener operates by itself, look for a stuck button on the remote control. If this fails, have a faulty circuit board checked and, if needed, replaced.

If your garage door opener opens a neighbor's garage door as well--or vice versa--check the owner's manual to learn if the frequency can be reset and how.

If the door doesn't open or close completely, look for and remove any obstructions and inspect the door for misaligned tracks, loose hardware, or uneven spring tension. Make sure the open and close limits and sensitivity are set correctly according to the owner's manual.

If the door reverses while closing, look for an obstruction and remove it. Make sure nothing (even a spider web) is blocking the electric eye. Make sure the close limit is set according to the owner's manual.

Fix-It Tip

Garage door openers made and installed in the past 10 years include a sensor that will force a closing door to reverse direction if something is blocking it. Older units may or may not automatically reverse direction depending on who made it and when. For safety, especially around children and pets, consider upgrading an older garage door opener to one with the latest safety features.

If the opener works too hard, increase spring tension or replace a bad spring. Have the door serviced to repair a worn chain sprocket or worm gear.

Maintaining the door itself will lessen the need for opener repairs (see below).

What Parts, Materials, and Tools Do I Need?

Replacement parts are available from larger hardware stores and specialty garage door opener retailers. The tools you will need to fix a garage door opener include these:

• Screwdrivers
• Wrenches
• Degreaser
• Mallet

What Are the Steps to Fixing It?

Most garage door opener systems have easily accessed adjustments.

Garage door maintenance:

1. Inspect and, if necessary, remove and clean dirty hinge rollers with degreaser or kerosene, replacing each assembly before removing the next.
2. Twice a year, lubricate the roller bearings and roller shaft with lightweight oil. Also remove any debris from the track.
3. Check and adjust the door lock bar. To adjust, loosen the screws and move the lock-bar guide bracket up or down as needed. Make sure that all screws are tight.
4. Inspect the door operation for smooth, uniform movement.
5. As needed, loosen mounting screws and use a mallet to straighten a misaligned track.