Posted By:
leonI use a Mars plastic eraser. They crumble when erasing but even at that you need to use it lightly....and try it on a sample or two before you do it on anything of value (just to be safe). They work well on light/regular pencil marks. Some of the real old pencil marks, such as on Herposheimer/E121 type cards, is done with a vintage oil? based lead and I haven't seen anything that would do well on those, but admittedly I only try the Mars and/or water and q-tip(for other things) and nothing else. Mars erasers are fairly cheap too. I think I got a lifetime supply for approx $5 but it's been several years...
edited to add that they are easy to find too. Any hobby store will have them or maybe even Wal-mart or Target.....