I have an UM2 + and the problem is that when i try to print something it goes all the way up and bangs in to the nozzle . I lower the build plate from the menu and i goes down and stops , no problem with lowering the build plate. But when i'm trying to calibrate the the build plate it goes up and do not stop like an inch from the nozzle, before i use to adjust (calibrate) it by hand ,but now it bangs into the nozzle !!!!
I checked the switch at the bottom it is ok!
I checked the connections on the board for the z axis it is connected!!
What could be the problem????