Since extension springs are determined by how much weight they each lift and the pulley system cuts this in half you need to replace your old springs with 200 pound extension springs.
How to replace a broken garage door extension spring.
Broken garage door extension springs make it difficult to open your garage door.
Garage door spring cost.
Garage door spring replacement costs 120 to 350 on average.
Repairing a broken garage door spring costs 40 to 80 for winding balancing and lubricating the springs.
This video will show you how to replace the extension springs on your garage door.
Keep in mind that a long metal spring is being stretched to the point that it will lift your entire garage door which can weigh several hundred pounds.