Chattering spider clutch

[JJBarbera@domain.elided]

For some time now the clutch in my '84 spider has been chattering during 
engagement, especially when the engine is warm and under load (e.g. starting 
on hills).  Does this indicate a worn or warped clutch?  I have also noticed 
some oil around the bell housing, and I'll assume it's coming from the 
crankcase since it doesn't smell like transmission oil.  Could an 
oil-contaminated clutch behave this way?  If the clutch does need to be 
replaced, what should I look out for?  I have a factory manual, a clutch 
alignment tool, and some significant experience with maintenance on this car. 
 Any help is greatly appreciated.

John Barbera
'84 Spider Veloce
'87 Audi Quattro

------------------------------