Hi Eric,

Yes, pull that black plastic box, too. Be careful when removing it because the bottom part can break off. You'll need a new O ring for this box ( goes on the bottom b/w the box and the engine block). Once the box is removed, you can use spray carb cleaner and a screwdriver to clean it. Spray the carb cleaner into the box, slosh it around, and tap on the sides with the handle of a screwdriver. This will loosen the chunks of gunk that are inside. It takes a while to really get the thing clean, but take your time. That should help anyway.

Let me know how it turns out.

Dave