I"m actually posting for friends who are firing our studio kiln and it's been stalled for almost 5 hours. Propane gas, firing went well through reduction but at 7 the bottom stalled and now the 9 is down on top and just soft on bottom. The temp wont' rise; they've tried everything. More gas, open damper, close damper. All leaving it be for at least 20 minutes before doing another adjustment. I told them that they lost their combustion and that they need to find the right "mix" of gas, air to get the kiln moving again but nothing is working.