Tefillin Battim Cracking on Bottom

tefillin bayis shel rosh bending
tefillin shel rosh bending on the bottom

This bayis is bending on the bottom in the wrong place. The hinge is supposed to be on the back of the maavarta, not on the bottom. This bayis is still kosher and can be used. If during tefillin work in the future, the soferim are careful, they may last for many years.