Filament Crossover on the Spool

A filament crossover occurs when a strand of filament slips underneath another layer on the spool, creating a mechanical knot. This prevents the spool from rotating freely, forcing the extruder motor to pull against the resistance of the tangled coil. Because the spool cannot unwind, the drive gear loses its ability to feed the filament, resulting in the gear slipping, grinding, and the characteristic clicking sound associated with under-extrusion.