So how do I go about checking if there's something wrong w/ my master cylinder. I know how to check the clutch slave but I'm not sure what else can go bad in the clutch system on the left side of the bike to cause my current problem (http://ducatimonsterforum.org/index.php?topic=12608.0).
Assuming you've got a coffin master, you can remove the reservoir lid, and when squeezing the lever *slowly*, you can see if there's fluid coming out of the large hole.
Most likely, the inner seal on the piston is compromised.
Yoyodyne may have a rebuild kit.
Or maybe cheaper in the long run to get a new master from 'em.
Coffin masters are relatively cheap brand new, around $100 with a new lever.