My home has several fireplaces and each has a cast-iron grate (or vent) along the sidewall of the firebox. In one fireplace, the grate has popped out— looks like it was grouted in when the house was built in 2004. Should I mix up some new grout, slather the edges and just stick it back in and hope it stays? And why are these “vents” in place, to begin with? The photos show the popped-out vent cover, now turned vertically and leaning against the vent hole.