To safely assess the functionality of your load cell, you can simply place or hang a known mass from the load cell to verify that the actual reading corresponds to the value of the mass. A mass of 20Kg or more is usually the safest bet for an ElectroPuls E1000 and E3000. You can always contact Instron support if you suspect you are having issues with your load cell. Remember: make sure you set appropriate limits whenever conducting any kind of test or load cell reading!
