What could be causing this to happen on a Kdrill- Milwaukee setup?
"Intermittent auger rotation slippage" When you say slippage, do you mean the drill keeps turning but the auger does not?
There is a drive bolt under the foam float. I can not imagine it shearing but I suppose that is possible, might check to see if the bolt is intact.
If the drill is stopping, I'd have the drill checked out at a service center.