Nothing gets past you, does it!
*LOL*
In defence of the changed plug my service manual for later model Maytag wringers does explain how and why to change plugs if required. This mainly had to do with grounding requirements.
As for the machine leaving aside the dull and pitted tub, small nicks/rust spots on outer enamel, the thing otherwise looks lightly used. If it were totally NIB the rollers would still have their coverings.
Close examination to our eyes does not show the dreaded oil leaks down legs. In fact all four casters look rather clean and shiny.
I'd say this is a "low use" machine. Certainly not "dead stock" from the 1940's.
To be fair perhaps the seller does not know Maytag sold wringer washers well into what? The 1980's? As such perhaps they are merely assuming it is from the 1940's.
Someone likely will decode the serial number and give us the low down.