My sizes are out

[dazp1976]

I ran Gcode to move X to 10mm then back to 0, 1000 times and same with Y and checked position everything seemed good.
http://www.mycncuk.com/threads/13525...399#post115399

I would have seen backlash with that check right?

Not really no. Even if it has backlash it will still follow the same pattern back and forth so you wouldn't notice.
Have a look at some vids that show how to properly check it.

If your sizes are out by more than say 0.2mm I'd say it wasn't a backlash issue. I've never really seen backlash values of more than 0.08mm which would make a circle smaller by only 0.16mm.