The pressure plate is in relatively good condition, aside from several raised (I guess bent up?) splines... could that have been enough to stop it from working? The ones are not severely raised, just a little higher than the others.
The thing is, it's almost like the clutch is engaged, but, while not attached, the drive shaft turns... you press the clutch in and nothing happens, it keeps turning.
Thanks for the info about the transmission turning! I kind of thought that might be the case, but wasn't sure...