Depending on the brand.
Garage door not closing on one side.
It is possible that the vertical track down the side has gone out of alignment and shifted due to a slightly loose lag screw.
Garage door opener malfunction or door has shifted.
There is one on each side of the door.
First check the sensor lights.
Push the door back to adjust the door and get the center aligned again.
There are of course many other problems that can keep your garage door from functioning properly.
If one side of the door is not in line with the other the door won t run smoothly in its tracks and when closed one side of the door won t close completely leaving an open gap.
Clutter or obstructions that block the sensor are the first problems to look for if your door won t close or in extreme cases open at all.
The extension springs are evenly matched and installed to keep the garage door properly aligned so that it runs smoothly throughout the entire length of the track and closes evenly.
This is of course a safety feature to prevent the heavy garage door crushing anyone or anything that might be in the pathway of the door when it comes down.
Garage door seal may be damaged 4.
By pushing the door back into position you should have made the vertical track straighten.
Garage door will not close all the way leaves gap at bottom 1.
Garage door sensors may not be aligned correctly 3.
Put a ladder under the door to make sure it won t close accidentally while you re working on it.
There may be a large gap of space between.
Garage floor may have cracked or shifted 2.
If the door goes up but you can t make it go down you probably need to adjust the sensors.
Bottom of the door is up on one side.
They both have lights and both lights should be on.
The door may rub up against the stop molding making it difficult to maneuver.
Side mounted extension springs are installed above the horizontal roller tracks on both sides of the door.
If anything interrupts this beam of light the garage door will not close and the ceiling light on the opener mechanism will flash as mentioned in the previous step.
The door might be hard to open and close due to it binding.
One of the more difficult problems for do it yourselfers to diagnose is a worn cable pulley on an extension spring door.