a "screw that never rusts" — sb who selflessly and wholeheartedly serves the Communist Party, like Lei Feng 雷鋒|雷锋[Lei2 Feng1], to whom the metaphor is attributed
of; ~'s (possessive particle) / (used after an attribute) / (used to form a nominal expression) / (used at the end of a declarative sentence for emphasis) / also pr. [di4] or [di5] in poetry and songs
silk / thread / trace / (cuisine) shreds or julienne strips / CL:條|条[tiao2] / classifier: a thread (of cloud, smoke etc), a bit, an iota, a hint (of sth) etc