I assume this was a training film, a very good idea and a new one in the 1940s. Such work used to be taught hands on and it would actually take years, working with a number of senior enginemen to know all you needed to know. These films may not have shortened that training period much but they would have standardized the routines and helped with sloppiness. There is a kind of Blue Collar romance to Worker films, even today, seeing good men doing good work is always enjoyable and really does encourage excellence. That's personal experience.
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