In Pictures: How to Clean and Retouch Old Photos w...
3. You will need to zoom in close enough to work on the affected area. Do this by adjusting the size ratio on the <i>Overview Palette</i> or by simply clicking the zoom + and - buttons. To view a certain part of your zoomed image move your cursor over the preview image and then click and drag the image.
In Pictures: How to Clean and Retouch Old Photos with Paint Shop Pro