This store has a good selection and correct naming for the images. It’s where I ordered mine: https://a.aliexpress.com/_msijd2i
Cerium Oxide is the way to go, but by hand, to avoid damaging the decal: https://www.watchuseek.com/threads/dw-5200c-9-restoration.5193999/?post_id=51853701&nested_view=1#post-51853701
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