Take a square sheet of 120 or so sand paper lay it on a flat surface like a glass table. Then while holding the housing from the top use light down presure and make figure 8's on the paper, this will sand off the chrome and insure a flat bottom. May take a full 5 to tem min to get all chrome off and flat. Them make sure all surfaces are dry and cleaned off wit carb cleaner, new gasket with something like permatex #2 or gaskacinch (sp)?? I don't like silicone at the t-stat base. Make sure where the head of the bolts touch are flat and use flat washers there if posible.
