My 9880 never quite got to that point. But when it was feeling cloggy, I would manually pull the shuttle assembly out of its parking position and onto about 3 layers of paper towels quite wet with distilled water or even Windex. Pat the wet towel down onto the black plastic stuff, and push down the sides so they won't grab the edge of the shuttle. A few swipes back and forth, then a fresh wet towel for a 10 to 15 minute soak. Of course the printer is off for all this. There's a little blue latch thing you have to manual release to get the head mobile. And don't forget to wipe the rubber squeegee thing and generally clean the parking station. I just hated all that stuff.
But I'm also thinking that for all colors to be down, something like your pressure pump may be bad. Never had that personally.
