Well, [Link: members.accessus.net] has a pretty good description of Sony service mode settings. You might want to look at:

AXIS (0) - Cleans up the red push & oranginess in the yellows.
AXPL (0) - Same as above but on newer models. Cleans up Reds/Yellows.
R-YR - Sets the amount of RED
R-YB - Sets the amount of RED

Remember to read all the usual warnings on the dangers with fooling around in service mode.