Mark, have you downloaded and installed the Sieg version of Mach3 that would have come with the machine on a disc as this has all the settings pre setup for the KX3 3000 and 5000.
When you click "Mach3 loader" it will come up with a Sieg logo on the screen and then give you a list of the machines from which to select according to what your max spindle speed is, this is then displayed bottom right of the mach3 screen.
Did you get your licence via ARC as the confirmation letter that is sent effectively says the same thing
Also have a look through this current thread about the other machines that have just come from ARC and my similar issues with my USB machine.
J
Edited By JasonB on 01/03/2019 13:32:49