This is an old revision of the document!
There are some recommendations on the EEVBlog forums here: http://www.eevblog.com/forum/index.php?topic=579.0
It can be really frustrating to try to fix a piece of expensive test equipment without a manual. There are lots of sources for service manuals, both free and not-free. Here are some of the ones I have found. Please only contribute sites to the not-free section that you have actually done business with (and think deserve a link.)