ADVENTURE: Monk Junk - can't find artifact?

[Bambii]

I'm currently in the Temple of Heaven for the Monk Junk quest. The problem is I already finished the dungeon doing Pangu's Axe quest so the shining keystone panel that I'm supposed to put the Temple of Heaven Keystone in is already filled. I tried just going to the area where the walkthrough said the treasure would be and examined every hole in the wall several times but my sim never finds the artifact. Am I out of luck for this quest? Is there a way to reset the keystone panel?