Hi! Can someone tell me is there an option for me to put firebrick or something else inside my pellet stove? The vermiculite board just cracked after only 1 season of use! I saw on another forum that castable refractory can be used to make a replacement. Agree? Are there any other options for insulation inside the stove for that part. US stove just never gets back to ANY email I send them. After shipping the part which is on sale for $35.00 costs $54.00. I am still using the stove, any problem doing that? Thanks, appreciate any input!!