Overhead garage doors, regardless of whether they roll up or swing up in one piece, work on a spring. The door moves on metal tracks on the garage rails, and a powerful spring or springs give the power. Many a time when the door doesn't work properly, repairs are usually straightforward and do not need garage door replacement. Here are some useful repair tips:
Step 1 to Repair a Garage Door
Check the metal tracks inside the garage. Take a look at the mounting sections that hold the tracks to the walls. If they're loose, fix the fasteners or screws at the brackets. Working inside the garage with the garage door shut, analyze the tracks for crimps, dents, or flat spots. If there are any damaged spots, pound them out with a rubber hammer, or with a mallet and a block of scrap wood. If the tracks are too much damaged, then they ought to be changed by someone who is a professional in garage door repair. 
Step 2 to Garage Door Repair
Check the tracks with a level to ensure they're appropriately aligned. Horizontal tracks should incline somewhat back towards the back of the garage; with roll-up doors, the vertical segments of track ought to be precisely plumb. The two tracks must be at a similar tallness on the garage walls. If the tracks are not appropriately adjusted, loosen but rather don't take out the screws or fasteners that hold the mounting sections, and tap the tracks precisely into position. Recheck the tracks with the level to ensure they're in the correct position; if everything seems fine, fix the screws or fasteners at the mounting sections.
Step 3 to Garage Door Repair
Clean the tracks with concentrated household cleaner to remove dirt and grease. Clean the rollers properly, and wipe the two tracks and rollers dry.
Step 4 to Garage Door Repair
Check for loose equipment, and fix as required. On swing-up doors, check the plates where the spring is mounted to make certain the screws are tight and fix any free screws. On roll-up doors, check the pivots that hold the sections of the door together; fix any free screws, and replace any damaged hinges. Do make sure that you have access to the problem of garage door repair precisely. If you are not sure if you can repair the garage door yourself, do call a professional from Garage Door Replacement Company to do the hard work. Sagging at one side of the door can frequently be corrected by servicing the hinges. If the wood is split at a hinge, take off the pivot and fill the cracks and the screw gaps with wood filler. Give the filler a chance to dry and afterward replace the pivot. If possible, move the pivot onto solid wood. Caution: If a roll-up door has just a single torsion spring, at the focal point of the door, don't attempt to repair it. The pressure is great to the point that the spring could harm you. For doors with this kind of spring, call an expert from Door Doctor for the garage door repair at (514) 631-3130.