Something to be wary of with the CJV when you are doing a print & cut:- if you alter the cut (tool) pressure on the fly it will shift the cutter head slightly, resulting in the subsequent cut line being 1-2mm out.
It's an annoying bug.
Always adjust the tool pressure before scanning reg marks, and if you still need to adjust the pressure, you'll need to then re-set the origin and re-scan the marks.
Apart from that, dig through the manual and work out how to calibrate it.
Check that you have latest firmware. Don't ask me where or how, but if you find out let me know!