I agree...leave it as-is. As far as I know there is no fool proof way of removing ink so you run the risk of doing more damage.
It is important to leave the note in it's original condition. Collectors appreciate original condtion banknotes. Once it is washed ( soaked in AB solution ), rubbed with erasers etc, it destroyed the surface sheen of the banknote. It will drop in both value and grade. Sometimes, it is rejected and deemed unacceptable by auction houses and collectors unless it is an extremely rare note. Some early world banknotes, e.g. Straits Settlements (1925 - 1930) series uses dye which change in colour from a nice purple to a pink when in contact with washing chemical solution mentioned earlier. I believe early banknotes uses inferior dye as compared to the dye using to print modern banknotes. I remember in one early public auction, a pink coloured banknote was classified as a colour trial which in fact it was suppose to be a purple coloured banknote. Little was known at that time on colour change due to washing. Motto : Keep it nice and original.
