The biggest issue with FED is jams, and this video will show one source of them and how to fix it to improve dispensing.
The most important thing is to make sure the pellet disk is completely stable inside the hopper. If you can wiggle it back and forth it's likely the motor is misaligned and the device may jam. In this case, either take it apart and try to align things better, or you may even need to re-print the FED front. See video for more info: