Bad top oilite bearing just under drive sprocket on opener power head.
Garage door keeps bouncing back up.
Your travel down setting needs to be adjusted.
Possible reasons why your garage door hits the floor then goes back up.
Bad pillow block bearing on torsion tube.
The two dials may have a picture of a house with a garage door next to them.
You want the one on the left.
It goes partway down reverses direction and goes back up again.
Missing wheels on door rollers.
A careless or rushed parking job can cause the car s bumper to block the sensor.
If these can t see each other when the door is almost shut it will send a signal to the garage door motor to open back up.
This is almost always the result of a dirty or obstructed safety feature.
You push the button to close the garage door.
Try the door and if it still re opens turn the same dial another complete revolution.
Sometimes the sensors will be in alignment and just as the door gets close to being shut it will vibrate enough to push one sensor off.
This setting basically controls how much force is allowed when closing the garage door.
Sometimes it can be torsion springs have relaxed some of its tension and door has become too heavy.
Turn it one complete turn clockwise.
Most likely there is an obstruction or motor sensitivity is incorrect.
As is the case with so many issues at the home there s no one reason why your garage door closes then opens.
Leaves twigs stuck on bottom section breaking beam.
Check how door operates in manual mode and run it up and down by hand feeling for heavy weight grabbing or binding points.