My treadle sewing machine is roughly 100 years old
My sister has one of those, it still worked fine (although she preferred the electric one just because it was more convenient.) Those things are just immortal. It is a damn shame to see what the world could be without planned obsolescence making everything into Ikea.
No emotional response. Something crazy starts happening and they're just dead calm, reacting sort of with a poker face. Usually that is a strong sign that it's not their first rodeo and sometimes in the past it has not turned out okay.