Was working on the shed, and the Hammer head gave way. I found the store where I originally bough it and bought a new handle. Modified it to fit and put it on. Now the hammer can do its job again
The part that goes inside the hammer has a slot in it when you get it.
You shove the hammer head down as far as you can onto the handle so that the base of the head rests on the part of the handle. You might have to widen the slot a tad depending on your handle and the hammer head to get it all the way down. Some of the slot part usually sticks up over the top of the hammer head at this point.
Saw off the excess so that it's flush with the top, and then you take the two small metal wedges that come with the handle and hammer them into the top of the handle, perpendicular to the hammer head, spaced evenly in the handle material.
Then it is customary to wild out and smack the shit out of things to test it.