My Electrolux Assistent N8, from 1978, also has a worm drive. Not plastic though, instead it has an electromechanical stall detector that shuts down the motor

My Electrolux Assistent N8, from 1978, also has a worm drive. Not plastic though, instead it has an electromechanical stall detector that shuts down the motor if it stalls. No need for sacrificial parts!