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=y9-_U3lQ09w
Universal product： X1,X2,X3,X4,X2plus, X4 plus, K1, K2,K3,K4,K1plus, K2plus, K3plus,K4plus, K7,K8
4.Can not feeding, nozzle is hot, E motor broken, replace E motor video:
Universal product： X1,X2,X3,X4,X2plus, X4 plus, K1, K2,K3,K4,K1plus, K2plus, K3plus,K4plus, K7,K8
5.When feeding , light not flash, nozzle not heating up, Nozzle replace video:
https://www.youtube.com/watch?v=IzpAT_1vT8I
Universal product： X1,X2,X3,X4,X2plus, X4 plus, K1, K2,K3,K4,K1plus, K2plus, K3plus,K4plus, K7,K8
6. Can not feeding because the tube under the gear is deformed, the filament can not enter into the nozzle, replace tube video：
Universal product： X1,X2,X3,X4,X2plus, X4 plus, K1, K2,K3,K4,K1plus, K2plus,K3plus,K4plus, K7,K8
7.Feeding has problem, Extruder set replace video:
Universal product： X1,X2,X3,X4,X2plus, X4 plus, K1, K2,K3,K4,K1plus, K2plus,K3plus,K4plus, K7,K8