I've had a Masterbuilt 7-in-1 for about six weeks now. I really like it--very versatile and turns out excellent food. From the start, though, the propane burner has produced a very yellow flame. I'd say it's about 30% blue and 70% yellow when high, maybe 40% blue and 60% yellow at the lowest setting. Very sooty. I contacted Masterbuilt (great customer service) and they sent me a new burner/regulator. Same problem. Both units burned yellow from the start so the problem isn't related to soot buildup or any kind of blockage. It burns bluest with the air adjustment set wide open so I can't give it any more air. I've tried different propane. I'm at 2500' elevation, temperatures have been mild. Any ideas?