There we are, now comes the fiddliest parts (Fun word, people should use it more)

((I will apologize as this is such a specific & requires all your hands, I did not have the ability to take pictures so the ones here are of it back together))

With one hand, hold the thread tight & with the other keep the base of it steady, you need to find the slot point in the center of the spindle (Picture one, red circle) & quickly let go of the thread on the bottom as you press it down onto that (making sure it does not unravel anywhere along the way)

Then, without removing the pressure from the top of the spindle you need to replace the metal thing (picture one, green circle), pressing it firmly down to make sure it stays tight in place

Lastly, make sure the little metal bit (picture two, red circle) is in place at the output slot (picture two, green circle)