If you've got a HA accuracy robot you should have smaller than 1 mm errors in all the working range. (Not a constant error but at max 1 mm).
That will be possible if the bases and tcp's are correctly done.
You can always do the mastering, some times transportation ends with small errors that a mastering solve.
You could try to make the tcp by calculus. When your robot is precise sometimes is even better doing it that way.
If everything fails, you can always call kuka tech support (if you have the robot under warranty) or try to contact metrology companies who could recalibrate the robot for you.
Regarding this last point, the HA robot is calibrated to himself, therefore any external adjustment in the base, tcp, artificial vision, sensors... Can decrease this precision.
With a HA robot you can be sure the precision will be under 1mm.
If yoiu recalibrate it you can achieve 0.3 (which is the best I've ever seen with a robot).
Hope this helps!
Sent from my BlackBerry 9300 using Tapatalk