part 8 is usually not that dirty at all, it is the part you remove to be able to clean the inside of the "Barrel", part 7, as all the oil that spins around in their builds up sludge on the inside of the barrel. it may be possible to poke into the barrel through the holes in part 8 with a little pick (or bent paperclip) to see if their is actually much buildup there prior to pulling part 8 and more than likely destroying the o-ring. might not have to clean it at all and therefore not pull it all apart.
I believe there are some oils that you shouldn't run because they dissolve sludge, thus potentially rendering the centrifugal filter useless... I think it may be the high detergent oils, but not sure what brands/types that might be. most people seem to run Rotella T diesel type dino oil.