Found this for pencil stain removal:
Pencil Marks (lead)
Try a soft eraser (Art Gum) for unwashable garments. Use a quality laundry powder or liquid on lead pencil marks, but never for indelible pencil. Soft pencil marks may be removed with a mixture of equal parts Dove liquid and Clorox 2 powder in warm or hot water. Soak thoroughly. Do not rub. Rinse completely. Formula 409 sprayed on, gently rubbed in with a soft cloth or toothbrush, then rinsed will also work.
For fresh pencil marks, try this:
• 1/4 cup water
• 3/4 cup rubbing alcohol
• 7-8 drops of Palmolive liquid detergent
Mix and apply with a toothbrush
Another suggestion: To remove pencil marks there is a recipe of 1 cup water, 2 tbs alcohol and 1 drop clear dishwashing liquid. I have had students tell me that the new clear Windex also works.
General Cleaning solution, also good for household cleaning: 3 tablespoons of household ammonia to a squirter bottle (1 quart) full of water.