When I get a new addition to my collection, I first clean up the whole motor starting from the top. I use WD-40 as a cleaning agent, as it is not really any good for lubrication. It works very well cleaning off old crud and dirt from motors. I spray on the WD-40 and spread it around by hand with no rag so it will clean and not simply get absorbed by using a rag. Use an old toothbrush to get into crevices, and let it sit a bit while you work on another area. Then start wiping it down with clean rags. WD-40 will not harm original paint or decals. Works for me!
I would reccomend using extreme caution if putting WD-40 on any painted surface that one aims to preserve because it removes oil residue, and paint commonly contains oil. While there a lot of different variants (with descriptions not mentioning paint), this one’s description says that it is not safe on all types of painted surfaces. https://wd40.ca/product/rust-release-penetrant
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