Yup, that's one site that's avaialble and here's another that I used:
www.dirtyblindman.com
I have one of those large picture windows with a hugemongous day/night shade that over time would no longer stay up. I was able to learn how to tighten the string anchors and solve the problem. I then checked and adjusted EVERY day/night shade in my 'tana.... Do you know how many there are? WOW, there are a lot. But all the shades work great now.
On the other hand I also had one day/night shade (fortunately it was a smaller living room one) where the string was too tight and broke. I ordered a kit from them and using the instructions on the site I was able to fix it. I be an 'xpert now (on small windows anyway).
Regards,
Art