To adjust garage door springs, place the door in the down position. To hold the door in place, put a C-clamp on the door track above the bottom roller. After this, adjust the collar on the center shaft and the torsion spring.
Find the adjustment collar on the center shaft, and put a metal rod into one of the holes. Make sure that the screw is set into a flat position. Keep the adjusting rod in position, and loosen the set screw.
Turn the collar with the rod to either tighten or loosen the spring, and remember how many turns you did. Tap on the rod that is holding the spring tension to walk the spring out. Tighten the set screw while holding the collar in the new position. Adjust the second spring in the same way.
To adjust the torsion spring, find the holes and two set screws that hold the torsion spring, place one tension rod into the first hole, hold the rod, and loosen the set screws. Place the second rod into the other hole, and move the collar to tighten or loosen the spring. Take one of the rods out, tighten the set screws again, and remove the other tension rod. Lubricate the springs with oil or grease.