I have an Xcarve at work that has had problems off and on for pretty much the whole time we have had it. It WAS a G-shield machine that we put the V2 upgrade kit into it last summer. The kids have really not tried to use it this year. I finally got into it to mess around and see why it has not been used. Last summer I completely rebuilt the machine.
The problems we have now, on large cuts, the X-axis has real problems with tracking. I have replaced the belt and checked tension on the belt.