Put the summary of the bug you're having here

What I expected to happen was...:
When removing a book, the signal would decrease by 1.

What actually happened was...:
While adding a book increases the signal by 1, removing a book bugs the first time. It only decreases by 1 when the second book is removed, meaning the Chiseled Bookshelf must be broken to reset the signal.

Steps to Reproduce:
1. Connect Redstone to a Chiseled Bookshelf.
2. Insert books.
3. Remove books.