Hmmmm thanks for trying.
I have an idea that might work but I don't know how to do it.
Use the magic selection wand to mark the burned out area and maybe make a separate layer, then create a brush from a portion of grey speckled background, then use that brush to paint across only the selected area (on the layer maybe), then blend the layers together.
That might over write the text, so maybe not. Perhaps I'll just live with it.