Broken torsion springs only happen (usually) when the springs are allowed to fatigue for a long period of time… it usually happens very slowly. If you periodically check the balance of your garage door (1-2 times) each year, you will most likely be able to see the springs fatiguing. As the torsion springs fatigue, they will cause the door to become more heavy. As the garage door becomes heavier, it will sink to the garage floor when you let go of it. Torsion springs in good condition will prevent the garage door from sliding down because they are still in good condition!