reply to u/BudgetSprinkles3689 at https://www.reddit.com/r/typewriters/comments/1nkbw85/serial_number_location/

What is the purpose of a serial number? What does it do for you? There are serial numbers on things all around you; do you know where all of those are? The VIN number on your vehicle maybe?

People now are only using them to approximate manufacturing dates for fun, but they were generally only used by the factory or repair people to identify specific machines and/or tie issues after manufacture back to production line problems. Do they need to be easily accessed or visible for these purposes? The people who really need them generally know exactly where they are and how to find them.

Sometimes they're used to create inventories for owners or in cases of theft, but these generally aren't common uses that need high visibility. Because they can be removed or defaced, should they be put in easily findable and accessible places?

Generally they're stamped in at the factory during production on integral parts of the machine during assembly. As a result, they can often be hidden or covered up by parts (especially exterior panels and body styling) added later. If it's on an exterior, easy-to-remove part, what good is it?

If it helps, here's a diagram of some common locations: