I inherited this Williams Sonoma SGIR27lp grill, came with a house we moved in. It is modified, instead of the grille and burners on the top, there is just a large stone/granite (?) plate. I managed to find a manual online, but it only has basic installation procedures. I am fairly handy, but have no experience with repairing grills. The large plate is glued with some super-strong cement/epoxy, I've been trying to cut underneath for an hour, but cannot separate it from the body. The body itself is all riveted, not a single screw that could help disassemble it from underneath. Ok, now to the specific questions: (a) any idea how to separate the top, in order to see what's left of the burner mechanism? or to disassemble from the bottom? (b) there is a metal pipe in the back, seemingly cut... (see the pic). what is it for?