I had these same issues; however, I think it was all related to the cold 0 degree temperatures I was smoking in. I brought the OBS in the garage and turned on the heater to warm the garage up to do some testing and seemed to work just fine when it was warmer. Not sure what the cold would have to do with the bisquettes not advancing, but I imagine it's like everything else in the cold weather......things just don't seem to work as well when it's so cold.
Were you maybe smoking in cold temps?