That is correct. The Selectric (and Selectric II and III) are entirely electric. Later Selectric variations, like the Mag Card II, introduced electronics in a s

That is correct. The Selectric (and Selectric II and III) are entirely electric. Later Selectric variations, like the Mag Card II, introduced electronics in a separate console or in a board fitting at the back of the machine, but the typewriter proper remained electromechanical, where the only electric part is the electric motor. The compensation tube is a cool design.