Please help! How do I remove felt tip pen from wall paper?

[Flumpf]

The wall paper is quite thick and textured, and has been painted over. My 3yo ds has drawn all over the wall with felt tips, Crayola pip squeaks to be precise, grape and black colours. I tried to use a baby wipe to get it off. A lot of the grape colour erased, but the black is not shifting. What else can I try please? Thanks.

I'm not sure what damage will be done to the wallpaper but I find a wd40 pen gets most things off. If you have any of the spray in perhaps you could try a little on a cloth. Anything wet could damage the paper though.