From: "You can do THE CUBE" by Patrick Bossert / published by Puffin.

To loosen up the cube if it's sticky to turn, turn the top slice 45 degs
and insert a screwdriver under one of the edge pieces (the one in the
middle) ....

(1) [] [] [] <- turn this slice 45 deg
    [] [] []
    [] [] []

(2) [] [] []
       ^ insert a screwdriver blade under that part and lift up until
it pops out.

(3) Then you can remove the two corner pices. Looking inside, you
can see the + shape of the cube mechanism. Put a BLOB of vaseline
inside.

(4) put the corner pieces back and the middle piece too. MAKE SURE
you get them in exactly as they were before you opened them up.
Otherwise,you WILL NOT be able to solve the cube!!

Hope this helps,
Edward

ps: PLEASE feel free to write to me if you're confused as this
is the best I can do without graphics.... (use graphics to
show but you can't here)