While the most thorough and sure way to eliminate the problem is by getting a structural engineer in to look at the garage take measurements and fix the sag.
Garage door sagging in the middle.
Getting your garage door in tight lean condition requires a bit if elbow grease and a good set of hand tools.
If the tracks have become misaligned then it s not too difficult to fix them.
In other cases the weight of the garage door in conjunction with an automatic garage door that is attached to the center of the door may be the cause of bowing.
You can do this.
A sagging garage header is essentially a structural engineering problem.
A wooden garage door may sag in the middle if it is bumped with a car or other large object in the garage but there are less obvious reasons that can cause such a door to sag.
Most sagging garage doors are the roll up variety as opposed to the single planked swing up variety.
There are several factors that may cause a garage door to bow in the center.
Indeed with a few turns of a screwdriver you can have that door level as concrete.
Garage door sagging in middle fixing misaligned tracks.
There are things you can do yourself to fix the problem although they may not be as permanent as having a professional fix it.