Ok took a look at my Zed...
Right on the TB's there are two silicon hoses. One set on the inside, one on the outside.
The one on the inside leads back underneith the plenum (about 3inches of silicon, then it goes into metal) the hose that connects is on the back.
The is another one on the outside of the TB's, that leads straight into another port hole on the plenum.
When I tore down my plenum, I recall taking the hose off the back first. Try that.
-Wes