The Isis Adventure

I've reviewed all the clues and have been jiggling to open the secret compartment to no avail. Did I miss a clue/step somewhere?
Thank you

No, that is it. Just keep jiggling the puzzle. There were a few copies that had sticky chambers, so as a point of reference, the chamber should have a very slight amount of movement to it. If it doesn't, you may want to try adding a very small amount of 3-in-1 oil between the equation chamber and the rest of the puzzle to help it move as you pull on it.