I have contacted ULS about this, but I figured posting here would be a good idea too.

One of our PLS 360 systems stopped working. It was engraving and then when our engraver when to check on it the head was moving back and forth like it was working but nothing was engraving. We unplugged it, removed the tube, reset the PC, reset the engraver and still nothing. While I was working on it I also noticed the the z axis is not working at all, the engraver told me it was working yesterday so I'm not sure if this is a related issue or not.

According to my records the tube was replaced this past January.