If it's faded thermal paper there is a spray you can get to restore... not sure what it is but the IRD here in NZ have it to restore old receipts that can no longer be viewed...
Message
Re: An Open Letter to Mouser
2011-02-15 by Andrew Sparrow
Yahoo Groups archive
Message
2011-02-15 by Andrew Sparrow
If it's faded thermal paper there is a spray you can get to restore... not sure what it is but the IRD here in NZ have it to restore old receipts that can no longer be viewed...