I echo Bruce's comments. This site has been around a while and I've always feared to some extent and have often held my breath before clicking on it if one day it would not exist anymore. It looks like that day may have come. I hope they have a copy of it and one way or another it will be able to reappear. It has helped a lot of people over the years and is referenced in quite a few related places on the net.That site seems to have gone into web site history. Unfortunate because it was such a useful tool for fans of the old Jakes.
I've seen posters on other forums making reference to doing research on it as late as July of last year but nothing comes up with the link now.
Back when I was doing a lot of work on old Jacobsens, Jacobsen/Textron customer service was very helpful in locating vintage operator manuals in their archives. Many of them were available in PDF form in their discontinued models lists. I don't know if they can help with providing a year, but who knows.
Take a look around on this page to see if you can find something useful.