Garage door problem? Garage door stops 10 inches from floor. Opener moves back and...

Garage door stops 10 inches from floor. Opener moves back and forth as door is moving. Small pieces of popcorn ceiling falling resting on car from introduction moving. Is the opener unpromising or is there another problem? No nought is blocking the door at the bottom.
Clogged hip bath drain?
Answers:    Three things come to mind. The door track rollers have substandard or the track is out of alignment. Was it recently undermined? Also, you have aide springs at the top of the door. They are there to compensate for the freight of the door so you can open it by foot, and it makes it easier for the opening. You may have one of these springs broken cause the door to travel ********. That would cause the juddering you are seeing.
Mosquito problem?
i have no clue