Got the printer all put together and all seems to be working well excpet filament will not advance through the extruder motor, through the white tube, and into the hot end. The gear in the extruder motor moves and I assume it is trying to feed the filament into the printer but the filament does not advance into the printer. I noticed that the little metal wheel oposite the gear has a grove in it. Is there supposed to be some sort of rubber washer slipped into this grove to help the gear get traction on the filament to move it forward? Everything else on the printer seems to be working fine. In fact my son (the printer was for his birthday today) skipped the extruder motor alltogether and manually fed the filament into the hotend by hand keeping the right amount of pressure on it during the whole print. He was able to get a print of the preloaded falcon that way. Lots of patience on his part to do that but we are looking for guidance on how to adjust the extruder motor so we don't have to do every print that way.