If the crystal is clear of information fits will rip out some more pages from various part of the book (all towards the back) so it isn't noticeable that there are 21 pages missing. Then he gets to work copying the information that was needed starting with the most recent and working his way back. When the charges run he switches to the crystal that Garrett found to finish the job.
Spoileruse magic device (1d20+6)[24]