Get a section of the rollers they use on assembly lines for packaging or moving things along.. put it on the steps and two people guide it down. Or two push it up. A friend of mine found one of these roller sections in a scrap yard and made getting gun safes in and out of his basement easier than a dolly!
Added...Here is the basic idea if no one knows what I'm talking about. You may have to cut a piece of plywood to fit in the lower cabinet lip. Just approximate size to fit different machines. I would trust this over that sling thing. Even if you had to adapt it a little to keep it in place.
