I have a crack in my prefab fireplace. It was repair by a previous owner. A chimney sweeper said a new panel should be installed. A contractor told me to get some furance cement and go over the area myself. Who's right? I usually use the fireplace 3 0r 4 times a year and have never had a problem for the last ten years It was repaired when I moved in.

So this is a prefab fireplace which is mostly metal with 4 cement panels insert to create a box, right? If you have a crack in a panel it does not mean the fire place is shot. You can buy replacement panels for most of them if you know the manufacturer