It came with quite a bit of surface rust.
So I disassembled it and soaked it in vinegar for several hours to remove the rust
After allowing it to dry I oiled the moving parts with gun oil (the only oil I had available)
And reassembled...It's much easier to read with the rust removed
I didn't even need a hammer to stamp the keys, I just struck it with the palm of my hand and that was enough to make a good imprint
(Yes I know I misspelled keypicking...my workbench wasn't bright enough to see the letters well)
Here's a link to my demo of the tool