Horn problems

[Bryan Carlson <bjc159s@nic.smsu.edu>]

Been trying to get my square in shape for inspection, and my task today
was the horn.  Both connections were bad (ground was simply off the
connection, the hot wire was actually broken at the male connection).
Took care of those and reconnected them to the horn, with no sound.  After
some testing, I found that the hot wire wasn't getting any juice, so I ran
a jumper directly to the hot lead (from fuse #11, key on) to see if it
would sound, and it didn't.  I also tried some other things, like taking
the panel off of the steering wheel and jumping the connection so I could 
fiddle without running back and forth to the cockpit.  I removed the horn
and tried direct hot (again from #11, key on) and ground leads, with no
avail.
After deciding that a new horn wouldn't cost all that much, I disassembled
the thing (six rusty screws), and found it to be surprisingly clean
inside. There was a contact to clean, but no other corrosion.  Put it back 
together, and no sound still.  Like I said, it seemed remarkably clean.

My question is:  what is there internally in the horn that could go bad?
Bentley says that
it's just an electromagnet striking the diaphragm that produces the sound,
and I don't see what it could be that is impeding my electromagnet from
doing it's thing.  I know that the connection that typically goes bad is
within the steering column, but in the case of my hot wire interruption,
that dosen't seem to be the deal.  Bentley also mentions a horn adjustment
screw.  I don't have the horn in front of me, so I haven't looked it over,
and the manual dosen't label the screw.  Where is it, and could a
maladjustment be the problem?  The only reason that I am fretting over
this is that the PO specifically stated that the horn still worked.  I
don't see how it could have, with the two bad connections, and the hot
wire not getting juice.  I'd just like some input.  What kind of prices
for a new horn should I be looking for, and will a horn from other VWs
work?

Thanks, 
Bryan
73 square (70 miles since rebuild, $400 in 1996, since you asked)