Ted, I can't see the pictures,not your fault, but some fault with my software, but I also have a way to remove helmet heads that I think may work a bit better than yours.
Apply some of your own saliva to the head, let it soak in for an hour or so and repeat. Carefully squeeze it open, and if that doesn't work use tweezers.
It works since saliva has LOTS of enzymes in it that will digest the outer shell of the helmet head, softening it up/
Try it, you might like it.
Carolyn