Use your hand to move the tensioner  fully to the left.
Put the sensor  less than 3/8" (9.5 mm) from the middle section of the belt [A].
Quickly pull your finger across the edge of the belt ("pluck" the belt like a guitar string). Do not let the sensor touch the belt. If you cannot make the necessary vibration with your finger, you can tap the belt with the handle of a screwdriver. Make sure the tension value shown on the meter is 75 lbf +/- 5. Adjust the tension adjustment nut  as necessary.
Measure the tension again. Adjust the nut  until the belt tension is correct. Torque the (2) 1/4-20 SHCS  to 12 ft-lb (16 N-m).
Install the front enclosure panel.