These sites do work or at least did yesterday. As you can see, I've divided it into their (singer's) major divisions.
Without any letter prefix:
http://www.singerco.com/support/mach...umbersNoLetter
With a single letter prefix:
http://www.singerco.com/support/mach...rsSingleLetter
With a double letter prefix:
http://www.singerco.com/support/mach...rsDoubleLetter
I sincerely hopes this helps any and all interested. Another good site is the Vintage Sewing Machine Shop site on the QB.