Snake Instantiate

Hi Everyone!
I have just found this great snake tutorial that I have tried to recreate:
And in the second video there is a section in the tutorial when we experiment with removing a part from the snake.
I tried to experiment with it so when the snake loses a part in the middle the rest of the snake should become a new snake, but no matter what I do I can’t seems to make it work.
No matter how I instantiate the new snake (duplicate or simply creating a new) the game object will not work and it will be missing the SnakeManager script.

Could someone please help me, how should I make it work?