I have a skutt firebox 8 – has only side heating elements. I’ve been trying to slump a small dish, about 3 1/2 X 3 1/2 and the sides angle down to a flat bottom. My problem is that I can’t seem to get the flat bottom. I get a curved dish that spins when you put it on a flat surface. I have a controller and have been increasing the hold time to try to get the definition in the glass I’m looking for. I’m up to 45 minutes at 1225 which still didn’t work. Any suggestions would be greatly appreciated!!