Most Keller calls start the same way: the door won't budge, or it drops fast the last foot before stopping hard. Some homeowners hear it first - a loud bang from the garage, usually the spring itself snapping under tension. Others notice it gradually: the opener straining longer than it used to, the door lifting slightly crooked, or a visible gap in the torsion spring where it's supposed to be a tight coil. On the newer end of Keller's housing stock, where insulated steel doors are heavier, a failing spring tends to show up as opener struggle before it shows up as a full break - the motor works harder each week until something gives. If your door has been making that grinding, straining sound for a while, that's usually the spring telling you it's close, not the opener being the problem.