I own a JCUT6090A, but I did away with the controller and used WinCNC.
If you don't mind, I would like for you to make a measured move. What I mean is, lower your tool to the table, mark the location, lift, tell the machine to move in either X or Y direction for 500 mm (or as far as you can).
Next measure that line and post here what the length is. I think you should be able to do correct resolution = commanded divided by actual multiplied by current resolution.
So, say you commanded 500mm but it moved 400mm. Correct res = 500/400*0.005. Correct res=1.25*0.005. Correct res=0.00625.
Say you commanded 500mm but it moved 1000mm. Correct resolution= 500/1000*0.005. Correct res=0.5*0.005. Correct res=0.0025.
Remember to plug in the numbers you get. I can't promise this will work, but it's the way I do mine.