okay,the "boost manifold" must be the chamber formed from the bottom plate and the upper bottom plate,The primary air comes from the air wash over the glass and a bit more from the boost manifold which is front and center above the grate.
the top is cast in a way as to form a tunnel for the air...then it loos like its routed to the ash drop area…..the joint between these two is discolored,
i just sealed it,i will fire it tomorrow and see if that changed anything.. this sucks.