Brian,

Without any visible leaks, it's difficult to diagnose
which cylinder is the culprit, but as Ken and others
have said, the two (master and slave) tend to fail
together.

For an overview of the system and several how-to's
describing such a replacement, I suggest you visit
John Meeks' excellent Vanagon resource, BTDT:
http://www.vanagonauts.com/index.phtml?catid=18

After skimming the Clutch Overview (penned by Yours
Truly, thank you very much), scroll down to the bottom
to find links to similar postings by other members and
myself on installing and bleeding the Slave & Master
Cylinders.

Good Luck!

Jeffrey Earl
1983 diesel Westfalia "Vanasazi"
http://www.vanthology.com/

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