The Polar 3D support site has detailed discussions of loading and unloading filament on Polar3D printers.
For Polar3D printers with serial numbers P3D02150 and higher, see:
Polar 3D support document “Loading and Unloading Filament”
For Polar3D printers with serial numbers P3D02000 - P3D02150, see:
Polar 3D support document “Loading and Unloading Filament”
For Polar3D printers with serial numbers P3D00000 - P3D02000, see: