Complex sentence: From 1974, he worked as foreman, senior foreman and chief of site at Leningrad Northern factory, then, from 1980 chief of site, chief of shop and chief of a technical department in a factory engaged in avant-garde research and production.
Split into simpler sentences: From 1974, he worked as foreman, senior foreman and chief of site at Leningrad Northern factory. From 1980 he successively moved from chief of site to chief of shop and chief of a technical department in a factory engaged in avant-garde research and production.