In Pictures: How to Clean and Retouch Old Photos w...
4. Select the <i>Clone</i> brush from the vertical toolbar and adjust the brush size to suit your work area. This will depend on the size and resolution of your picture. A good tip is to set the <i>Opacity</i> on the Clone brush to 50 per cent as this will have a relatively gentle effect and will make it easier to blend the cloned area to the original.
In Pictures: How to Clean and Retouch Old Photos with Paint Shop Pro