The other day one of our operators went to home out the SVC-2000 right after start-up. He uses the multi axis button to home out, and all move about the same time. A second or so after the machine began to move, an extremely loud, vibrating/grinding noise came from somewhere in the inside of machine. I wasn't there, but the whole shop heard it and all agreed it was "Very Loud" everyone thought he crashed the spindle hard! There was no alarms other then the machine went into E-stop mode. we powered Off/On and all is fine...The machine hasn't done it since. Has anyone encountered anything like this or know what might be happening here? The ball screws and bearings sound fine. Also, it was so intense I guess the nearby operators could feel it vibrate.