By wade shaddy updated december 19 2018 you push the button to close the garage door.
Garage door opener starts then reverses.
The 2 nd cause is the closing force could be set too light and the normal tension of the closed position exceeds what the door believes to be allowable tension.
When the opener reverses the screw turns the opposite way and the nut travels back.
The photo eyes send an infrared beam across the bottom of your garage door opening if that beam is broken the door will reverse.
There may be two nuts on one track.
Photo eyes or safety sensors are mounted to the track on either side of the garage door about 6 inches up from the ground.
It goes partway down reverses direction and goes back up again.
One for the opening limit and one for the closing limit.
However if the door travels all the way closed and then reverses look to the 2 nd 3 rd possible causes.
This happens from both the read more.
Reverses on its own.
I have a garage door opener stanley d1000 a07 date 98523 i hit the wall button or remote button and it hums starts to move then stops and reverses itself then stops.