If you’re interested in how the inner mechanics of an Underwood typewriter work, Animagraff’s cutaway 3D animations are an excellent exploration: https://www.youtube.com/watch?v=yKpIwi1UUIk

All of Jacob O’Neal’s videos in the series are excellent, like the pages from a Popular Mechanics cutaway brought to life.

The build process: https://www.youtube.com/watch?v=HzI2GgTZAfE

Oh neat. I’d been gifted a few of these model kits over the years and they’re a delight to build.