If you're a Filawinder user, maybe you've experimented that if the produced filament,
isn't perfectly straight, when it goes through the PTFE tube, probably it will drag the
tube toward the spool, risking to break the servo. In fact the tube diameter's is larger
than the servo arm slot. This accessory, tightly screwed to the Filawinder basement,
will block the PTFE allowing only the passage of the filament to the spool.
Be careful, if the produced filament is too twisted and curled, you risk to
damage the motor, but if not, you'll surely save the servo.