I assumed it was where you got your model ID photo from. The site has a large Kz400/440 model identifier page.
I just go to Kz400.com. It used to be a full-fledged forum etc. but it's a lot of work and money to keep that up, and after Odd Ivar passed away, other members kept it going for awhile, admirably, but I think it was just too much work and cost to keep up. Now it's more of a simple webpage. Some reported viruses on the downloads there, but I've been on the site and downloaded manuals without problems as recently as last year.
This is a link to the 1978 workshop manual, but I haven't tested out the downloads for that manual.
Maybe download the manual to a phone or something to see if it causes a problem. Or perhaps someone else could chime in on how safe the manuals are from that site.
kz400.com/WorkshopManFrameset-5.html