Hi, I am trying to replace the extruder with a better quality one than what comes stock with the printer. The issue I’m running into is that the stepper motor shaft does not have a flat side, it’s just round with the gear built on it. I guess this is not the case will all ender 2 pros? When trying to look for a new stepper motor, it seems difficult to know if what I am purchasing is actually for my model printer. Could someone verify for me exactly what I need to get for this printer?