ack. This feeder has higher torque and better control of filament feed than the previous model. In order to guide the filament properly through the feeder into the Bowden tube and print head, it is important that the tension on the feeder is set correctly. If the tension is too high, it means that the knurled wheel of the feeder will dig into the filament, through which it flattens or gets stuck. This is called grinding. To prevent grinding of the filament, ensure that the white insert clip at the right side of the feeder is set in the middle. When you use other materials than materials delivered by Ultimaker, you might have to adjust the feeder tension slightly for the best results.