This was what I wanted to show you because now the cornor notches can be seen clearly. In the second and third photo.
In this photo you can see two lines leaving the notch in a Y shape. These need to be removed or they will contribute to the ear and tabs damage. Now more than ever go slow the tool will do damage. If you just made the point you should not be notching because you are tired and it is easy to make mistakes and get in a hurry. Set the stone down and take a break before you continue. When you start again remind yourself of the three goals 1 platform 2 cornors 3 watch that tool.
Now this photo show the corners removed.