I'm so relieved oxalic acid worked at bleaching the wood. When I first put it on, it didn't look like it was working and I was so disappointed. But it turns out the key was to put the solution on and go away and do something else. =)
I also spent about an hour trying to clean paint off knobsets and hinges. We weren't so lucky as some folks. Our door hardware doesn't look to be solid brass. Maybe it was once brass-plated but they look to be in fairly bad shape and mostly black at this point. We may need to go buy new hinges. I'm planning to look into having the knobsets re-plated mostly because the doors are already fitted to this hardware.