Hitachi 27CX22B-501 Entire screen has a greenish tint. menu colour adjustments do nothing.

You did not say whether it is bright, overdriven with retrace lines in it. I've have seen what I just described in Magnavox (common) and Zenith TVs. If you're unit looks like what I just described it could be one of the following problems. The fix for the Magnavox was a 10 ohm safety resistor in the green drive circuit (on CRT board). For the zenith it was the drive transistor on the main circuit board prior to the gun but after the video IC. In either case you will need an O-Scope to signal trace the video circuit to find the culprit. If this is within your expertise go for it, safely of course. If not, get a professional to do it.