^ this seems to narrow it down to an extruder issue (either driver, wires, motor, or gear engagement) and not anything to do with the nozzle or hotend
^ this concerns me, cause I've had extruder wire issues before that were a little trick to troubleshoot because it would seem fine when stationary (e.g. continuity checked out fine), but then would have issues when moving (flexing the wires).
to check it, you can try via pronterface or octopi or however you connect your printer to a pc, send this through terminal (after heating up hotend and homing first)
G1 X150 Y150 Z20 F2400
G92 ;resets extruder position
G1 E20 F300 ;extrudes 20mm slowly (can change F value [mm/min] to change extrusion speed
alternately, you can have it move while extruding and see if it does anything...
G28 ;have to home first
G1 X20 Y20 Z20 F2400 ;get in position
G1 X200 E20 F600; moves to X=200mm and extrudes 20mm of filament
or move diagonally
G1 X20 Y20 Z20 F2400
G1 X200 Y200 E20 F600; moves to X=200mm Y=200mm and extrudes 20mm of filament
all of those are from memory, so check the g-code wiki to make sure it makes sense to you