I cannot tell if the Z-truck upgrade solved the air carving issue because now the close cover error can't be cleared. I took it all back apart and checked all of the connections from the cover on out. I think it is a problem with the white plug on the cut off cable - the plastic is crumbling and it may not be making a tight connection. I have ordered a new one and the other switch cable just in case. I ordered a new card just in case also. I am now wondering if I should have ordered a new head termination electronics board. If the cable is not plugging in well enough it may not be the cable side of the plug. By the time I get this up and running it will be a completely new machine inside. I just wanna carve not be the electronics expert on how to fix it. sigh.