Hi Chris,
Below is a link to a youtube channel, Mrpete222 or otherwise known as tubalcain. He is a retired industrial arts teacher that has some great how to's. In particular this one is on replacing hammer handles. Thought you would like it. Sorry about your spare time though, once you start watching him, he is a bit addictive.
https://www.youtube.com/watch?v=CuS5hfVK4H4