I have an old, yet unused, Whitfield/Pyro Reflections WG2 gas fireplace insert (serial #WG24074) in my basement. My guess is that it was put in when the home was built in 1983. I am now finishing my basement and want to put tile around the fireplace. The installer left three unmortared joints in the base bricks directly under the fireplace. I am trying to locate an installation manual to determine if those slots need to be there for some reason or if I can mortar the bricks together and tile over it. Any help would be greatly appreciated. Thank you!