The classic Leica reference books have the Hektor f2.5 50mm standard lens as appearing in 1931 , peaking in 1932, and tailing off in production in 1940. There was a possible revival in 1946-1948 when 71 may have been made which may be due to using up of surplus production in stock after the War, BUT the very fact that these later lenses were made cannot be substantiated according to reliable sources. I wonder if the post war 71 units were older lenses returned for coating?
Now l have come across a comment by Fr. Willy Frerk the Editor of Photofreund who was a correspondent of English Magazines in pre- war days. This is dated January 1938 when it is reported that the Hektor has been so much surpassed by the faster Summar f2.0 standard lens the'it is hardly ever asked for now' and has been discontinued. Given that Leica made some 27000 Summar lenses that year it certainly seems to have had it's day. Not only that but the company made 11000 of its new and so much better Summitar only the next year!