Thank you for asking.
I've done a lot of research and I've just about found the solution, now I just have to imagine how it works in my head.
Below is the result of my research for those who are interested:
I found exploded diagrams of toyota embroiderers and therefore found their name.
Then it got easier!
Their names: thread catcher and ass'y picker (assembly picker).
ass'y picker :
thread catcher :