1. Set the Light / Dark (LT /DK) switch to the Dark position (Down).2. Set the sensitivity control to the mid-point position. Test with material in place after installation. Some materials work best with the sensitivity control fully clockwise.3. Slightly loosen the sensor mount (the plastic nut behind the mounting plate). Slowly change the sensor angle downward and observe that the loop gets larger. If a smaller loop is desired, move the sensor angle upward, then put some of the material back onto the roll by manually turning the roll. Continue to adjust the sensor angle until the loop is the desired size. Tighten the sensor mount when done. The loop size may also be changed by adjusting the sensitivity control. A lower setting makes a bigger loop, and a higher setting makes a smaller loop.