The inside sensor (with the green light) is the sending sensor and the outside sensor (with the red light) is the receiving sensor. When the elevator is running, the red light should be flashing (one flash per paddle passing by the sensor). If not, probably a faulty sensor. If lenses are dirty, that could also be due to scratched lenses. The lenses typically last about one good season, maybe two depending on crop rotation and soil type. Make sure you change out both (sender and receiver),about $60 pair, can't remember what mine cost. The yield sensor controls the moisture sensor. Once lenses have been changed perform the set zero yield function under the scale icon with the separator and feederhouse running at full throttle. This is the zero cal. funtion and initializes the sensors. If the warning continues, you could have a bad sensor. There is also the possibility that the ECM is bad too, might need reflashed or replaced. 1) Replace lenses (both) 2) check for a green and red light on the sensors and make sure that the red light is flashing when the elevator is operating a full throttle 3) Set zero yield (zero cal.) 4) following the zer cal. function, turn off seperator and notice if the moisture sensor activates (it should perform a system check once the separator is tuned off. The cylinder will activate indicating the system check. 5) Make sure that the moisture sensor set screw is turned all the way out At the most all of this will cost a few hundered dollars vs. a few thousand to get a new system.