If in fact the augers quit turning with the impeller still running, it is either both shear bolts have failed or the auger gear box needs work. With the unit off, try and rotate the auger. Does it turn the impeller shaft, skip teeth or spin freely?Can 1 auger be turned independently of the other? Yes, the gear box should have lube in it. If it is an MTD product, the last spec I saw is for OO grease. Some originally came w/ 90 w gear oil and is ok to use. I don't like mixing lubes, so take a look at what you have. If the box died, lube won't help now.

Hello tomplum.

Thanks for the info. I just turned the impeller and could hear/feel the engine turn over and the augers turn slightly. The augers do not turn by themselves and the shear bolts are fine now. I also noticed that at one side of the gear box the weld at the end of the auger has broken. I think that must have happened when I caught a small (about 1/2" dia.) twig that broke the shear bolts a couple of weeks ago.

So I'm thinking that the gear box is in bad shape.