I'm firing a Rhode downdraft front load gas kiln. Propane. Not certain what the US equivalent might be. I can't get an even top to bottom firing. Temperature top is plus one cone. It has peeps top and bottom of the door. Top gets indications of steady reduction, bottom little if any. I start the firing with the damper 1/2 closed, am able to make a small damper adjustment (close as I increase gas) once I reach about 800c and both the top peep and the chimney show solid yellow flame, little smoke for a couple minutes then just flame. Good overall temperature rise. It only stalls if I push the damper to where the kiln smokes. Would like to understand how to get better temperature balance, reduction balance?