Start with what the door is doing
A bang followed by a door that feels extremely heavy points toward a spring failure. A door hanging lower on one side can indicate a cable problem. Blinking opener lights often point to sensors, but an opener that strains may simply be trying to lift a badly balanced door.
Those clues narrow the diagnosis. They do not replace an inspection. Springs, cables, drums, rollers, hinges, tracks, seals and the opener all affect one another.
- Stop using a crooked or partly fallen door
- Do not loosen bottom brackets or wound springs
- Disconnect the opener only when the door can be controlled safely
- Keep people and vehicles clear of the opening
