Install the stiffening strut on top of the top section of steel doors with the section lying flat. Then install the opener bracket that replaces the center bracket between the top two sections. While you’re working on the sections, protect them from scratches by putting carpet scraps on top of your sawhorses. Now, slide the rollers into the roller brackets.
From a big-box store, basic garage door cables can run between $8 and $20, depending on the product. Your pro may charge you a different cost if they provide the cables. Your cables may not need to be replaced if they have simply come off the track, but broken cables will need to be completely removed and replaced. In either instance, the pros will need to secure or take down the door; unwind the springs; reset or replace the rollers, cables, and drums; and then wind the springs once more. For example, a pro could reset cables that have come off the track for $129.99. The average national cost for a garage door repair specialist is $80 - $110 per hour and the typical cost to replace a broken garage door cable is anywhere from $130 to $200.
Gather the supplies and tools needed for changing the springs safely. In addition to the torsion springs you'll need a minimum of one or two 10" vise grips, an adjustable wrench, and two 1/2" X 18" winding bars. Most hardware stores sell 1/2" X 36" steel rods that can be cut in half. You'll also need a firm ladder and a rag for cleaning your hands. A ruler and a file may also be necessary; a socket wrench and sockets would shorten the time required. Finally, make sure your garage is lighted well.
Garage door springs come in two styles: torsion (see above), which mounts on the header above the door, and extension (Photo 1), which floats above the upper roller track. In the past, extension springs were safer to install but didn’t have containment cables running through the center of the spring. Without cable, these springs become dangerous, heavy whips when they break. They also tend to be noisier than torsion springs, and we recommend you use them only if you don’t have the 12 in. of headroom above the door that a torsion spring requires.

4.4 Take the spring on the left and place it at the left end of the door as pictured here. Notice that the end of the wire points to the right toward the center of the door. This is a right wind torsion spring. It will go above the garage door on the left side of the spring anchor bracket. The winding cone at the other end of this spring is usually painted red.