The decals on that machine are in really great shape so be real careful how and with what you clean it. Don't use any chemicals, alcohol, or anything with abrasives on it. That WILL destroy the decals.
For a machine like that I'd remove all the plated parts then use cotton swabs or make up removing pads and sewing machine oil only to clean it. Then if I felt it needed it I'd study Glenn's tutorials on redoing the Japan finish found here:
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http://www.quiltingboard.com/vintage...s-t193635.html }
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http://www.quiltingboard.com/vintage...s-t186522.html }
Joe