Eric, the stuff we found with our 82 year old chimney when we took out the fireplace was amazing. The mortar was no more than sand in some locations. And there were 3 other takeoffs from various stove connections that had been "sort of" sealed up. In some cases this meant simply a piece of sheetrock or wood! in front of a metal plug. I never ran that chimney without a full liner and am very glad in retrospect I didn't consider trying to get away without one. It's not worth it.