We purchased a Hearthstone Heritage last winter. It has worked great. My husband noticed this morning that there was a rather large hole in the interior top...between the vented pipes. I checked it out this eve and yes it is quite large. He feels he may have hit it with a log but I cannot see how that could be avoided. We plan to order a replacement part? Has anyone had this happen and how difficult is it to replace this part? Thanks for your expertise.