I was given a push model new in the box from the Ol' Lady's grandma. I always like playing with them growing up so I gladly accepted it. It was made in the last 10 years and is still in production. The manufacturer slips my mind at the moment.
After reading some of the instructions, I came across the sharpening section. It stated that to sharpen this particular mower, you would remove a wheel and insert the hex axle stub into a drill chuck. You would rotate the blade drum in reverse with the drill at a slow speed until the blade edges were back to proper sharpness. I assume this is back lapping as mentioned above?