Hi,
Way back in 2014 "JudyTheSewer" posted: "Hopefully, someone does have information on the "W" serial numbers and then you will know a bit more about your machines too."
I did find a website with dating information on Singer's Bridgeport, Conn. factory's "W" serial numbered machines:
http://sew2go.com/singerdate.htm
I hope that you still have your Singer 319W machine.... I acquired mine in September of 2002, and I still have it:
[ATTACH=CONFIG]571533[/ATTACH]