Don't use the denatured alcohol on that machine to clean it! The purpose of the alcohol is to "melt" the shellac, and it will silver/remove the decals that are exposed! Not only that, but to clean with those products would simply embed any dirt into the finish. Sewing machine oil...more sewing machine oil...and then clean with sewing machine oil!
That is shellac that's flaking off, and once you have it cleaned, then use Skip's linseed oil/denatured alcohol combination to French polish the machine. Muv's videos are really good for cleaning these old girls too!
As for the age of the machine?
If you and I are of a "like age"...that machine could very well have been a wedding or "first child" gift to your grandmother... I know my mother was born in 1925...just think, your mother's baby clothes were probably sewn on that machine! What a wonderful treasure!