Before going the sandpaper route try a more aggressive paste...
"WENOL" polishing paste (from Germany, I've only seen it once) seems to be a bit more agressive than MAAS. There are others too, "Simichrome" by Happich and "Metal Glo" is another one. They're all inexpensive, so it doesn't hurt to keep the full stable.
Also don't forget the Cape Cod polishing clothes they are quite abrasive and can do the job...
All good advice. I'd like to know more about the Cape Cod cloth and where to get it. Never tried it and would like to see for myself what it does.
The word "sandpaper" scares most, and for a good reason. Usually a too aggressive grit is picked to start out with and the results get real discouraging. You certainly won't hurt the blade with a 2,000 grit or a 30 micron paper or film.
I do remember warning readers of my cd to always pick the least aggressive approach first. After you do this fix-it stuff for a while, you can look at a razor and just know if you can buff the marks out or start slapping it with 220 grit paper. I have even gone down to 150 grit for some, but if you need paper more aggressive than that, you may want to consider abandoning ship.