removing debris from auger

how do you clean the worm tube ? I need to get shale or fines cleaned out. breaking sheer pins left and right.
when I get coal {rice} the delivery people chute it in coal pin but they shoveled some shale from driveway into coal bin.
can I backfeed the auger manually or is that a bad idea?

Did you look at the thread on the top of this section. It gives you breakdown of certain parts, not sure if it's the same model, but
might help in dis-assembly

Pictorial: Pipe and Worm Package

Lift your drive pawl and check pawl out of the way and crank it backwards. Are your two pipes tight together inside the coupling? Wet coal is also hard on pins.

my coupler looks like the top picture, I did loosen the set screws but the coupler won't move or slide