How can I tell if my garage door spring is broken and who should repair it?

A broken garage door spring is often easy to recognize. Many homeowners report hearing a loud popping sound from the garage when the spring snaps. You may also notice a visible separation in the spring coil. When a spring fails, the door may refuse to open, or the opener may strain while trying to lift it. Spring replacement should always be handled by a trained garage door technician due to the high tension involved.