here is a new teardown video from me,
this design idea is so special and rare it is worth to mention here:
https://youtu.be/nZnH6WrpSAUi think it is from 1975-1985, name of designer unknown
the push-buttons for all voltages is a really special idea, I have not seen anything like this before,
it dont really work in real life if you ask me :-)
this one is full of loose connections and unstable behaviours, i did not repair it for now, since its low useability for my lab / collection.