How serious is it if the heat shield in back of the insert is warped in a Napoleon Insert 1402 P-K, brand new, three weeks in use. No problem until last night. The stove had gotten very hot, and not much later heard a "boing." Waited til morning til things cooled down. Pulled off the surround and looked around. Noticed the heat shield in back of stove (not inside firebox) behind the stovepipe and heat exchanger had curled along the edge and fallen loose. I wouldn't care except it's impeding the flow of air being pushed out by the fan. Is this reparable? Is their a way to know if the heat exchanger was damaged--cracked--as well? Anyone have any experience with this? Thanks. [email protected]