Wanted to add...
For the purists who would argue that these things should be kept in their original form (and I used to be one of them...)
The tears and missing chunks of paper are not "original" to the piece. So it is already "altered" in some fashion. I just don't see any harm in enhancing/improving its appearance. I also think that with paper items, we need to be a bit more forgiving of restoration than with other forms of memorabilia.
Just my .02
