Hmm, begs the question: if part of a yukkuri gets quickly reattached to the paste inside, it retains functionality?
I know, I know, pastries. But I like the thought of it restoring functions much like a clean cut finger in a human (which, if properly preserved and quickly reattached, regains mobility).
Overwhelmingly the part will "die" or lose enchantment. That said, there's been a few examples of restoration. There is even one picture here where ( I think) a nest of yus in some grass is hit by a Weed Eater and the face of one is grafted to the back of another.