Darkening I don't think any one color has dropped out, the whole picture has gotten to be quite dark.

adjust the color go to the menu and change the color meter to darker or lighter and your welcome

the set needs to have an adjustment in the panel voltages. this must be done by a qualified tech. the panel has now gotten it's full aging and now needs to be adjusted. this adjustment does not need to be adjusted again after this has been done.

sounds like you have disintegrated one of the clutches in your transmission and are running bare plates against eachother, get that transmission rebuilt or replaced

YOUR TV HAS A CORRUPTER MICRO CONTROLER
YOU MUST GO TO A SERVICE CENTER THE SERVICE CENTER WITH A SPECIAL TOOL THATS AVAILABLE BY PANASONIC WILL REPROGRAMME YOUR EEPROM THIS SHOULD NOT COST MORE THAN 100 DOLLARS IT IS NOT NECESSARY TO OPEN TV

Check your custom settings in the Lexmark printer utility. I have a different model but mine allows for lightening and darkening of output. Variations in ink density and paper differences make this almost a necessity.

I suggest you first take a clean, white cloth wetted with a stronger solvent such as 'Oops,' carburator or brake cleaner (with these two, DON"T overspray, they will damage plastic and paint) and wipe the drum inside to make sure there is not some gunk adhering that is gradually depositing itself with each wash cycle.
If you have a shade-tree mechanic in the family, they may have gotten a gob of grease on clothing that transfered to the inside of your machine.
If you don't find enough on the cloth to have caused the problem, I think you have lost a seal on the drum-side of the transmission.

sony had a recall on this set see if this is one of yours
http://esupport.sony.com/perl/news-item.pl?news_id=24

do you happen to have any speakers of any size within about 3 feet in any direction of the tv?? move them if so, I have large speakers about 5 feet from my tv at home and i still get some distortion once in a while with red and dark green streaks.

use the advanced options page and reset the factor blue and red convergence defaults then do re apply the auto color defaults color at first it seemed very red (which is good because red was the missing factor in the green picture) but after reseting all the color and tints to the normal ranges I then reset the color auto correct again and all seems fine.

How old is the TV? More than 6-7 yrs? Then it's time to do a trade in. But if you are very attached to it, get a Technician to recondition the Picture Tube. This may give it life for another couple of years. You could also ask a technician to check the DC filter Capacitor for the HT line to the Video Drive circuits. Over time this capacitor dries out and also causes a darkening of the picture. It is normaslly a 100 mfd 160V capacitor.