I have the standard 50 lb. bin, but the stove will shut down on no pellets with 20-25 lbs. left in the bin. It's easy enough to manually pile them over the feed but you would think the slope of the bin walls would make this unnecessary. I'm wondering if it's the pellets (it's a new stove and our first ton) or the bin or maybe our gravity isn't what it should be. Any idea's from the experts? If I do lubricate the walls, what would I use that will not dissolve the pellets?