Check the alignment of the sensors by placing them on a flat surface, at least 2' apart, and breaking the beam with a thick object (e.g., hardcover book). Verify that the LED beams are visible through their respective holes and not obstructed by the enclosure.
Check the sensor batteries. The life expectancy of TB06 batteries is 1-2 years with normal use. Unless preceded by a "Use By" stamp, the date displayed on the battery is the manufactured date. Verify that the batteries are 3.6V AA Lithium.
