Some of my fire bricks in my regency insert have cracks in them. I was thinking about changing them all out as I would need 16 of the same size and the unit is 6 years old. Should I bother or should I just leave them alone. I found bricks made by Rutland that are fairly cheap compaired to the one that come from Regency the manufacturer. Is there a difference? Am I over reacting by changing them out?