Diagnosis
Smoke leakage indicates a compromised lid seal or a warped lid/hood. The CGG-7400 does not have a gasket. Leakage is often due to the lid not sitting flush on the firebox because of debris on the mating surface or loose hinges.
How to Fix It
Clean the entire perimeter where the lid meets the firebox. Remove all grease and carbon buildup from both surfaces. Check the hinge bolts on both sides of the lid where they attach to the firebox. Tighten any loose bolts with a wrench. Open and close the lid several times to see if it settles into a better alignment.
If That Didn't Work
The lid or firebox may have warped from high heat. Inspect the lid for visible gaps when closed. Minor warping is common and does not significantly affect cooking performance. The primary risk is heat loss, not safety.
Heads Up
Some smoke escape is normal, especially in windy conditions. A major gap that allows significant heat loss will make temperature control difficult. There is no user-serviceable gasket to replace on this model.