There's two options that I have seen done, but unfortunately they both involve the tranny being taken apart. Option one is to take the tranny to a shop that can flush your unit with fresh fluid mixed with a detergent, it can be expensive, but it will save you the time of cleaning. Option two sucks (do it all yourself), it will save you the most money, but you'll be sitting there for hours with break parts cleaner and a brass brush. The last C-4 I built for a friend I took completely apart, put everything in a large plastic storage tote with a heave duty degreaser/super hot water mix, and scrubbed the hell out of the unit. I hope someone knows more because I would like to know a better way myself...