I have the cetus3d MK2 standard and I replaced the CPU with a brand new one because mine stopped working. After a succesful install, when I initialize the machine, the Z goes up and and up and up and never stops - until it CLANKS - until I stop the machine. Cetus support is unable to help. I wonder if they sent me a CPU for an extended model. I had bought 3 spare CPUs and they all do the same behavior. Z axis does not stop and clanks.