Door closes then immediately reopens a short distance

Safety first: Keep people and vehicles clear while testing.

Step-by-step:

• Observe LEDs: Watch the photocell indicator LEDs while the door closes. If they flicker or go out just before full close, alignment is marginal.
• Reposition brackets: Adjust the photocell mounting so that the beam is not grazed by the door, hinges, or bottom seal when closed.
• Shield from sunlight: If direct sun hits the receiver, fit a small shade or hood (without blocking the beam) or slightly angle the sensors to reduce glare.
• Retest: Run several close cycles and confirm the door stays closed.