The position of the additional weight is essential for the measuring system. The choice of the additional weight determines the measuring range. The measuring instrument is only calibrated if the additional weight is attached correctly. Push the additional weight onto the pendulum as far as it will go. The serial number on the weight should point towards the pendulum joint. Fix it at this point with the set screws installed. A deviating position has a direct influence on the splitting energy of the system as well as additional undesired natural oscillations.