The Behmor is fairly sensitive to Voltage, and seems to die off a bit with age too. I have had no problems taking 12 oz into second crack on the P1 setting before. Another trick is to put a 2x4 under the front legs to tip it back, that way the center of bean mass is closer to the heating element, so when it's in it's 'off' cycle when it starts cycling the burner for temp control, they are closer to the heat source so suck up a bit more.
Although embarrassing, I will admit, Ive set mine on fire a few times by inattention. With that said, the things used to be built like a tank, a good cleaning out and it ran fine. Just run it through a cleaning cycle to burn the soot out of the exhaust element.
Aaron