In my experience, the holders of valid copyrights on outdated material tend
to go easy on casual swaps of copies among hobbyists. However, if it looks
like someone intends to make a living selling copies of their stuff, AND the
owner still stands to make significant income from said stuff, then they
might get lawyers involved, probably starting with a "cease and desist"
letter.

A couple of years ago, I got an email from someone at SAMS (the Photofact
people) noting that I had posted a portion of a 1950s SAMS TV schematic on
my website. This was a restoration article and the schematic snip
illustrated a specific problem that I had solved. The SAMS guy was very
nice, and only asked that I give them credit for having supplied the
schematic. This, despite the fact that SAMS is alive and well, and it
typically sells that sort of schematic for around $25 a pop. They probably
figured that the miniscule amount of free advertising for long-obsolete
schematics outweighed the hassle/expense of having some higher-paid employee
call me long distance to make the same request :-) The schematic snippet
wasn't that important to the article anyhow, so I simply deleted it from the
web article.

It's harder than you might imagine to find out who -- if anyone -- still
holds a valid copyright to old material. I have tried looking a couple of
times, and ran out of patience long before I found an answer.

It never occurred to me to look on Ebay for a schematic or manual. I have
had good luck with suppliers such as http://www.w7fg.com/ and
http://agtannenbaum.com/ and http://www.tubesandmore.com/ .

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html