Can't re-arrange plates on Pedestal!

ok, this is driving me nuts! I'm sure there is a very easy solution but I cannot, for the life of me, pick up the plates and re-arrange them once I have initially placed them on the pedestal for the first time. This is near the beginning of the game, inside the asteroid after you go through the shaft!

Seems like once I put them down, there are stuck there! Whenever I click the cursor on them, Low repeatedly says, "this metal plate has got to have some purpose" And that's it.

Also, is there any key that you can press that will bypass the some of the dialogue? I have, on more than one occasion, wished this was possible because a lot of what is said is repeated ad nauseum by the characters.