Question: My wife and I just moved to a newer house (9 years old) and we have an acclaim in the living room. We want to start using it so I cleaned it out this weekend. Inside the main chamber at the bottom back is a soft material that is flaking off and when I ran my fingers around this area, it felt like the stiff foam you get in a flower arrangement? What is this stuff and do I need to replace it? Also, how can I tell if I have one of the upgraded newer models or if it is the older more troublesome model I saw referenced on your site? I plan to buy a manual for the stove but I'm puzzled about this stuff. Answer: If the stove has cast iron liners, then it's the older model. The newer model has firebrick all around the stove inside. The material you mentioned is part of the secondary combustion chamber, which is behind the cast read firewall of the stove. You can see and touch it through the area where the flame goes up the inside rear of the stove. If it's fairly intact, you don't have to replace it. The part that goes first is usually the cast iron rear three-piece liner right above that area. Check this for warpage.