Spindle Encoder Lost
Spindle orientation is different positions when changing the tool, the most this problem is encoder loose, or belt, pulley 's encoder
Turn off power, take off the ship metal cover the spindle motor. Checking 2 set screws encoder loose and tight it back, and check belt,pulley's encoder
We have to set spindle orientation again, before run machine. How to set spindle orientation? Look article Set Orientation.