I'm not familiar with the 7100 since I have a 4100, but I have had issues where fuel does not slide down the feed chute smoothly and could cause backup/jam issues. What it seems to be is sometimes during my high wind conditions which cause the flame to back up into the feed chute, it seems to deposit soot and who knows what else. I've ordered a draft kit hoping to prevent this in the future, but the soot buildup seems to slow fuel down and I've had to clean it out a few times. I tried a used toothbrush, but that's not stiff enough, so I pulled out a copper scouring pad and rubbed it around in the tube as far as my fingers go and after that a lot of gunk comes off and fuel falls down freely again.
Not sure if this is your issue, but if the flame does occasionally go up into the fuel chute or is dirty with soot and doesn't feel smooth if you put your finger up there (while the stove is cold of course

), that might be it. Corn being heavier than pellets may not be as adversely affected, but may not come down as fast as normal.
Also, the fact that there's play on the auger (at least on my 4100) indicates that the bushing is clean so that's a good thing. I've seen my auger start binding up and it will travel up and lose that inch and then I have to take the auger/auger motor apart in order to clean gunk out of the bushing and reassemble it. Another indicator I've seen of a clogged bushing is that fuel feeds much slower (putting it on 10 suddenly seems like it's feeding at the old 1!)
These two things are part of my monthly/bimonthly maintenance.