How do you adjust or replace garage door springs?

There are two different styles of garage door springs used on sectional doors... TORSION and SIDE-MOUNTED.

Torsion springs are mounted on a stationary metal shaft located above and parallel to the top of the garage door frame. They are attached on one end to a stationary plate located above the center of the door frame. The springs extend along the shaft, and work by twisting as the garage door closes by means of cables attached to each side of the lowest garage door panel. This tension makes it easier to lift the garage door from its closed position.

Side mounted springs are long heavy springs mounted on each side of the upper garage door track. Through the use of pulleys, they perform the same function as the torsion springs... they come under tension when the garage door is closed to make lifting the door easier.