Posted By:
Jason Las unassailable?!

First, try using a very small flat-head screwdriver, inserting into the seam and twisting to pry open. Otherwise, I then turn to snipping the corners with a pair of pliers (wear protective eye glasses/goggles)
As Matt mentioned, I used to advocate sawing the case in half, removing the two halves of the card, and then gluing back together, but I have lost too much money on the re-grade. I do, however, now own an impressive collection of otherwise high-value Authentic cards that present miserably!