Pls. I need to know when we should change the sensor factor for ABB Mag flow meter. In fact I am facing almost 50% decrease in reading. I changed the Main PCB also but no change. So now I change sensor factor from 2.4 to 4.2 and reading is now Ok. I assume the sensor (1000 mm dia) which is 25 years old now has become unresponsive. So is it the correct method to adjust the flow sensor? Pls. guide.