Hi Rob
I just tested it and please use the screw driver to rotate 1 direction first and make it tight. then you can release the screw slowly. here is my output. thanks.
sensor_value = 519
sensor_value = 518
sensor_value = 516
sensor_value = 519
sensor_value = 518
sensor_value = 518
sensor_value = 518
sensor_value = 519
sensor_value = 519
sensor_value = 518
sensor_value = 518
sensor_value = 519
sensor_value = 518
sensor_value = 517
sensor_value = 518
sensor_value = 518
sensor_value = 517