Sorry to hear of the chip death - especially from another MAZE2 user!
I have one of the nonconductive (mica) shims in place under my MAZE2, and the block doesn't seem to move at all with the springs only partially compressed, but the shim probably has very little to do with keeping the block steady, because the four rubber pads are much thicker than the shim. Did your CPU still have the four rubber pads on it? Seems like they play a big part in stabilizing the waterblock and keeping it from rocking any.
I also have a 3/8 thick neoprene ring around the socket for condensation prevention, which gets compressed slightly by the block, that may also help prevent rocking.
Another consideration may be the stiffness of the water hoses, I read that you are using 1/2-inch I.D. tubing, I am only using 3/8ths I.D., and chose very soft tubing: Mcmaster part#: 5554K17 - Tygon Laboratory PVC clear 3/8 tubing. The soft tubing may be more likely to simply bend instead of leveraging the block, while larger diameter, or stiffer tubing may put more force on the block when the tubing is moved??
Don't need a "hard" hose when watercooling...