I was using a mousepad and 80 grit sandpaper...I moved up to 220 then to 800
The magic marker trick and mousepad method works great but the problem is that the factory edge on busse knives are generally thick. The mousepad method is really meant for convex edges, that's not to say it won't work on a v-edge, but you really have to work at it for days if you want lower the shoulder on a factory edge. Once the shoulder is gone, the mousepad (since it's soft) will conform to the whole convex edge. After you get it back from HD, the mousepad method will work a lot better.
I don't know if my explanation made sense, but it should make better sense once you sharpen the knife after HD convexes it.