If this has happened to you you can add more concrete to the floor in order to bring it back up to the right level.
How to adjust how far a garage door closes.
There are two ways that you can adjust garage door track.
When the garage door opens about halfway or 5 feet from the ground and stops the up limit switch needs to be adjusted.
This will help you create a flat and level surface so the gap will close.
These may be on the side of the box but are usually at the rear.
2 you can adjust the track so that the door aligns with the weatherstripping.
These limits must be set correctly for the door height to have a proper seal as well as to allow for adequate clearance.
If the door was closing too quickly move the spring to the next higher hole on the bracket.
Look for two limit adjustment screws.
How to do a simple adjustment on a garage door opener.
How to adjust a garage door to close completely.
Open the garage door and watch it closely as it opens.
Identify the switches by the up or open.
Place a stepladder beneath the box portion of the garage door opener.
With a screwdriver adjust these screws.
Once the spring is free of tension remove from its track hanger.
Find the limit switch and the adjustment screws that will allow you to adjust the position where your door stops when it closes.
Check that it is straight.
Adjust the springs on both sides of the door the same way.
It is possible that the vertical track down the side has gone out of alignment and shifted due to a slightly loose lag screw.
A related topic would be adjusting garage door springs.
Each garage door opener has limits which control the opening and closing heights of the door.
1 you can align the track with the door itself so that the rollers work properly.
By pushing the door back into position you should have made the vertical track straighten.
To adjust your door close force use a step ladder to access your door closer.
If it was opening too quickly move it to the next lower hole.
You may need a flashlight.
Push the door back to adjust the door and get the center aligned again.
If there s a slight gap at the bottom of your garage door then a garage door threshold is a great option.
Install a garage door threshold.