Bob, I'm weighing in a bit late but I often used the scalpel method with great success. The trick is to "shave" away the offending area gradually, then go back in and spot with a stippling effect. You must practice on a scrap print first. I used to make exhibition prints for a professional railroad photographer, and his prints looked like the negs had been run over by a locomotive. I hated doing editions for him. By the time I was done working a print, I'd be cross-eyed but at least he could not find where I worked the prints over, only if you held the print at a glare angle. Eventually he allowed me to spot the backside of his negatives, but passed away suddenly. I prefer this over scraping the print surface.