Tilt the unit on all axes, making a note of the extreme largest and smallest values you can achieve on each axis.

If the min & max on any one axis do not have the same magnitude, that's one problem.

If each axis is balanced, but their max magnitudes are different, that's another problem.

If all axes are balanced and have close to the same magnitude, yet your sum-of-squares still isn't constant, that's a third problem.

Which is it?