As expected, there's not much we can do for color calibration on this pj since it has no CMS (color management system).
For the measurements I was able to make, the color calibration is not bad at all. It is pretty close to accepted standards. Could be better, but again there's not much we can do about it.
As far I can tell, there are only 2 controls that are available on the HD33 for color calibration and they are color and tint. The 3 primary colors are controlled all together with the Color control, which pretty much maxes out saturation at +5 (red measurements are steady past that value), and tint can slightly improve the balance of the 3 secondary colors at -1.
Final ajsustments: I'd leave Color at +8 and reduce Tint a notch at -1.
Try that, along with greyscale calibration posted above and let me know what you think...