Tool Post could not locked

The 4 station tool post could not locked in position, sometimes the CNC system alarms: tool post change time too long, sometimes there is no any alarm, and it often crash the turning tool bit. every time need to push the tool after change the position, or it will crash again.

Check the tool post wiring, nothing wrong was found, then uninstall the tool post, then we found the plane bearing inside was broken, change the tool post then the machine back to normal.