I pulled my surround off to check the status of my block off plate and a lot of the sealant I used has cracked and crumbled off. I used both Fire Block and Funrnace Cement, and both cracked. I was thinking about using that Hi Temp silicone Gasket maker, but I wanted to check with you guys first. I thought that might be better because it is more pliable. What do you guys think?