I have two large butts cooking this am. My ET-73 says the grid temp is 304 and the dome temp is saying 400. Is it possible for the difference to be that large? The darn grid temp was to low so I bumped the bottom vent open a little and it jumped almost a 100 degrees in about 5 min. Watching it closely now to see if it falls back. I want the grid temp to be 275. Ideas?