Here is the 3D model for the #onOffswitch for an #IBMSelectricII on Thingiverse: https://www.thingiverse.com/thing:7083085
IBM Selectric II On/Off Rocker Switch by howtophil

This is a rocker on/off switch (and probably the other rocker switches) for an IBM Selectric II I have that had a broken switch. It works for me. You may need to tweak it.This may work with other Selectric models but I don't own those, so I do not know.Here it is in TinkerCAD: https://www.tinkercad.com/things/3PvTtziZ1tq-selectric-ii-onoff-rocker-switchYou can modify the model as you need :)

Thingiverse