Years ago some company made a tool just for that purpose.  It had a mini-cylinder from a porta-power in the middle, with two large rounded plates on the outsides.  You could change plates for different size augers.  A long piece of black pipe served as the pusher, and supplied the cylinder with hydraulic fluid.  You might find a bin company near you that has that tool, there used to be some around, according to the posts made on ag discussion groups years ago.

I like the jack idea, sounds as if it would work for much cheaper price.

I would think the porta-power deal would work well for the tube that was not straight, if the plates were long enough, but never heard of it being tried.