My lab has purchased a pellet extruder from your company. We have tried the PLA extrusion test, but PLA couldn't be extruded. We found that the PLA couldn't go into the melt zone, although the screw kept rotating. Do you think the diameter of PLA pellets should be reduced? Also, when I was testing, I didn't add the fan attached to the extruder. Do you think the fan would help the pellets enter into the melt zone, especially the one called thermal shock fan? Thank you!