The thing with the behmore it IS cycling off and on pretty constantly through a better part of the roast cycle, especially once you enter crack range. This means it supposedly IS getting up to temp, at least it thinks so. Perhaps the air outside the drum is hot nuff to say it is but inside with the beans it aint? Maybe a fan inside to blow more of the hot air around inside to get more of it to the beans? Or possibly have the temp cycle at say 15 degrees higher to add more heat to the beans?
not sure but something should not be too hard to figure out.
Aaron