I've pulled the K66C from my S2554. And I personallythink the worst downfall in this trans is the paper-like filters they use in the trans. Any thing can easily clog these thus making the pump starve for oil. And if that happens...things will not move quite well. lol
Anyway, i'm going to replace the filters and the center case (pump distribution block) and see what happens.
To be quite honest..as blocked as these filters are I would put money on it thats my problem.
I'll keep it updated. Waiting for parts at the moment.