Take some rubber tubing and shove it all the way to bottom and use a wet vac to suck the gunk out. Throw more water and soap as needed to get it all rinsed out. I wouldn't take that thing out unless all else fails. I have even used 2 tubes before (many years ago) forcing water down one while vacuuming on the other to get stuff out of hard to reach places. Kiatechinfo.com ought to show some idea for removal if it comes to that. Good luck.