I've had my Masterbuilt Pro Dual Fuel 2 door for about 10 months now, and I've used it probably about 10 times. The only modification that I've done was to fill the chip pan with lava rock. I've only smoked with chunk wood so far. The first few times that I smoked, my biggest issue was keeping the temp down in the 225-240 range. I got pretty good at it by regulating the airflow with the dampers, and using the water pan. The past 2 times that I've smoked, I've had a very hard time getting the smoker up over 200. Last time I eventually got it, and successfully smoked a couple of pork butts. This time, I stalled out at about 190. I let it go a few hours, tinkering with it the whole time, trying to get the temp up, but I was having a hell of a time. Eventually I gave up, foiled the butts a bit early, and tossed them in the oven. I let it cool down, pulled out the pan, lit it up, and watched the flame. The flame was very inconsistent, it would go from a good, tight blue flame with very small yellow tips, to big wavy yellow flames, without touching the control knob. When I did adjust the knob, it had little to no effect. I leaned it back and looked underneath, there doesn't seem to be an airflow adjustment. The burner is relatively clean, and the output from the control knob is inserted in the burner tube the way that I think is correct. Does anyone have any suggestions as to what the issue might be? Bad regulator? Bad control knob? Any help is appreciated. Thanks!