Please see the attached document if your problem is related to inspecting/ clearing a blockage:
Some possible reasons that cause the failure to load filament.
Clogged Nozzle or Hot end
Extruder Motor Not Engaging
Incorrect Extruder Tension
Filament Jam or Tangling
Wrong Filament Type or Diameter
Excessive Resistance in the Extruder Path
Incorrect or Broken PTFE Tube (for Bowden Systems)
Hot end Heat Not Reaching Proper Temperature
Blocked or Dirty Filament Path (Hot end or Extruder Gear or Barrel)
Incorrect Loading Procedure
Extruder Gear Slipping or Worn Out