The SENSOR BEAMS are located 4″-6″ off the floor next to the vertical track. If your garage door opener goes down just a few inches and goes back up or won’t go down at all, your SENSOR BEAM LENS may have an obstruction that prevents the invisible beam from functioning.
Does your garage door travel a few inches down and then go back up? Check the sensor beams for blockage or debris. Use a clean dry cloth and gently clean each lens.
Does your garage door travel within a few feet of the floor and reverses? Check the bottom of the garage door for debris or a pull down rope that might swing in front of the sensor beams, breaking the infrared beam.