I hauled the machine outside to the back patio for cleaning – a good idea since it was filthy and greasy and dusty.
I removed the snap-off top plate and took a good look at the type hammers / type bars. I saw dust and goo and animal hair, but nothing bent or broken.
First off, I used a small air compressor to blow out the dust.
While the air compressor cleared out the larger debris, most of the dust remained because it was embedded in grime and goo and oil. I put a bunch of clean paper towels under my work surface and then poured a little denatured alcohol into a cup. With a little brush, I painted inside all around the levers and type hammers / type bars.
The dirtiest spots were the slots in the “smile” – they were filled with sticky goo.
I then used an old toothbrush to scrub around.
While I scrubbed, I gently struck the movable keys to loosen them up. They began to move more easily and black gunk dripped out from underneath. For the frozen keys, I was able to very gently lift them up out of the goo with my finger tips. Fortunately I didn’t have any bent hammers, just very dirty ones.

With its neighbor hammers lifted, I gently pry up a frozen key and loosen it from the goo. Check out the rust. This typewriter has lived a hard life.
After a lot of painting and scrubbing and working the hammers / type bars up and down, the keys began to move freely, hitting the platen easily and returning to their home reliably.
Make sure your work table is protected with a cloth or paper towels. Be careful to not get denatured alcohol on the outside of your typewriter – it could ruin the finish!
Here are videos that I found invaluable to my cleaning efforts: