Recently, I too have experienced the "non digging" auger. In my case it is a Befco M2 9" auger without any downforce kit. I've become very suspicious of the replacable auger point. As a test, I removed the auger point and I was able to dig down another 6" right away (until the middle was so compacted with dirt it stopped). I don't think that my auger point is a very good design. It looks kinda like a large wood screw. However the threads of this screw are very wide, in some places over .5" thick. These thick threads (and the blunt tip) really cut down on the downward pressure that the auger can generate. It's not much different than trying to push a smooth cone shape (point first) into the ground. I'm going to see if I can modify the auger point so that I can put some sort of replacable cutting edge on it. Maybe two flights bolted onto the tip at angles...
Peter