1.can't feed and retract， check reason：
2.feed not good during printing， check reason：
3.Can not feeding and retract, nozzle is hot, the filament stuck into gear：
https://www.youtube.com/watch?v=foyYLOC7L5o
Universal product：NANO, NANO Plus, Minnie, K5
4.Can not feeding, nozzle is hot, E motor broken, replace E motor video:
https://www.youtube.com/watch?v=d24x4KfrgYI&t=78s
Universal product：NANO, NANO Plus, Minnie,K5
5.When feeding , light not flash, nozzle not heating up, Nozzle replace video:
https://www.youtube.com/watch?v=W7arsOrbl10&t=34s
Universal product：NANO, NANO Plus, Minnie,K5
6.Extruder whole set replace video:
Universal product：NANO, NANO Plus, Minnie,K5