Ceiling-mounted garage door opener with its rail and power cord

Opener chain or belt sagging, slapping, or too tight

A loose chain slaps and can skip teeth; an overtightened chain or belt loads the motor and sprocket and can trigger faults. Set tension with the door disconnected, then run a full cycle and the reversal test.

Cross-checked ~30 min easyBrands: LiftMaster, Chamberlain, Genie, All

Before you start

Close the door before pulling the release; a door with a broken spring can fall.
Unplug the opener before touching the drive.
Never adjust springs or cables (blocked).

Diagnostic steps

Unlock all 7 steps with expected values

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

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