A looped-cord system includes a beaded cord having a set of beads connected in series to form a loop with a space between each pair of adjacent beads. In one embodiment a stop sized to fit within the space between a pair of adjacent beads is attached to a housing. A resilient finger located opposite the stop pushes a portion of the beaded cord adjacent to and not engaging the sprocket against the stop so the stop is within a space between a pair of adjacent beads, thereby preventing movement of the cord loop. Applying tension to the cord loop overcomes the resilient finger and moves the cord away from the stop enabling movement of the cord loop. In another embodiment a key engages the sprocket preventing the sprocket from turning until tension is applied to the cord loop by proper installation of the tensioner on the cord loop.