Robofil 290P what`s needed for autothreading ?

It appears our machine has some autothreading hardware,
namely the last few belt driven rollers, i believe the middle one of the three is for wire feed during rethreading,
as far as i know there is also a small black pipe on the top head behind the wire guide.
What is used to cut the wire for rethreading ?

I`m pretty much clueless here, could someone please give me an idea of whats needed to get the function to work.

thanks for any help.