Without seeing a much higher resolution image its hard to say what your problem is so any ideas on a fix is simply a guess.
When I need to retouch an image where there is either distinct grain or some texture of the original paper being resolved by the scanner the only tool I've found effective is the Clone tool. I generally use it as follows:
1. Disable all layers in the PS image except the actual image (e.g. Adjustment layers, layers that create borders, ...)
2. Create a new empty layer just above the image layer.
3. Select the Clone tool and check the "Use all layers" box.
4. Optionally, set the fill on the clone tool to something less than 100%. I often use values in the 25-75% range; generally higher when I'm cloning grainy or textured portions of an image.
5. Select (highlight) the new empty layer and use the clone tool to sample from a good portion of the image (face in your case) and paint of a damaged section.
With the "Use all layers" box checked, PS will sample from all visible layers (this is why you must hide/disable all Adjustment layers) but paint only on the selected layer. As a result, your cloned data is on a separate layer and can be erased if you make a mistake. You can also create different new layers for differing sections of the image so that face retouching and uniform retouching are on their own layers and can be revealed or hidden independently.
By sampling a spot on a cheek to paint on the scratched other cheek, you clone the grain and all leaving a much more convincing patch. You have to constantly retarget the source (ALT-click to set target) for each repaired area so that the target has the appropriate tone to match the spot you're trying to fix.
