I think it was 1956 when the “Red Dot Indicator” began. The stitch length indicator (pointer) was added to the Singer 401A the same year, as far as I can tell. I think it’s interesting that the Singer 301A continued to be made without any additional stitch length indicator (pointer), and continued as far as I can tell, for the length of its run to 1957. Maybe they already had decided that the 301A production would end the following year?
CD in Oklahoma