Did anybody have ever made a little sanding in the fade area of a playfield like if the paint is crack, in the spot where you clean as hard as you can with no big result. i made an attempt on a small spot with #400 sandpaper and that seem to work. So i just want a know if somebody have ever try this before . thanks. Or if somebody have a better idea , i would be glad to ear it !!!!

You may want to read this comparison of sandpaper vs. Magic Eraser:

http://arcadearchive.com/pinball/magic/

On my late 70's and early 80's Bally pins, I often sand areas of the playfield to even out areas where "planking" has occurred.  I might use 400 grit or maybe 600 or 800 depending on the situation.  Of course, I will then touch up the paint and clearcoat.  A playfield is just wood afterall, and as long as you have the means to get it back to normal, there's nothing wrong ( in my books ) with a good old-fashioned sanding session.  

The magic eraser look great , i will give it a try today .. thanks