Jennifer --
I just went through this over the summer with my 84 Westy.  I replaced the
slave cylinder, and a few weeks later the master cylinder went.  Go figure!
Replacement is fairly straight forward, but the Bentley manual tells you to
use a pressure bleeder.  I didn't.  I used the old partner method.  This was
OK until about a month later, when my clutch began to fail.  I figured, OK,
two cylinders, now the clutch.  I went to my VW mechanic, and he gave me a
tongue lashing.  Seems the use of the pressure bleeder is necessary, else bad
things happen in the nether parts of the system.  He pressure-bled the system,
and the bad things went away.

Have fun!

Doug