How to sharpen the blade of an old pencil sharpener?

I don't want to buy a new one as I don't have time this week to head to the store to get a new one. I want to just fix this one so I don't have to buy another. I'm just a bit impatient because I have a portfolio I need to work on, but none of my remaining pencils are sharp enough to do the shading. Can I sharpen the blade just enough? Or is there something else wrong with it? (There is nothing stuck in it. Well, not anymore. I emptied it and now it looks fine, but it still doesn't work very well.)