My Wife and I were both getting sick and she kept saying she could smell smoke when the stove was dampened down for night burn. I pulled the top stones off and found the 2 stone near the side feed door were not sealed. I pulled all the top stones and found a couple other spots where smoke was leaking past the seal's/ cement sealant. what I need to know know is how, and what product do I need to re-seal the stones when I put them back in?