Now I am not a Pork Butt man, only do one about every 2-3 years, but am I recalling correctly Tony used to state the a smaller butt takes longer to smoke. ? Is a 6# considered smaller? Could this be a combination of issues, extension cord, small butt, possible checking smoker temp while on the down side of the swing? Just food for thought questions. I know this for a fact, once you get past this hurdle, you will definitely use your #1 more than once a year!
Happier Smoking!