@Butch this is what I did
When I first made my mini I drilled a bunch of holes on the bottom then I used the steamer platform(what you put the food on if it was a seamer) to set my terra cota plate on. This worked at times and sometimes I just could not get the heat up. So last year I did this.
I noticed this the most when I switched from a SJG bottom to a SJS(I did this because grilling on a gold kinda sucked)
Original config
Steamer platform pic
w/ Terra Cata plate
The mod that works great
Cut out bottom
Install bolts for diffuser plate
New diffuser plate with bolts to keep it from shifting all over