Toshiba RPTV 40PW8 picture problem

Hi All,
I am new to this forum and as might be guessed, I have a problem.
I have two 40PW8's, both about 5 years old; one I have had from new and is more or less ok except that it has a tendency to wander between the several EXT positions (EXT 1, 2, 3, 1/6 etc.)., but I can put up with that if necessary.
The other one, however was given to me by an emigrating neighbour. He originally tried to sell it to me just before he emigrated to Europe last August but we couldn't agree a price and I had not recently seen it working at that time. The TV was left in his unheated house from August to the end of November when he came back for a visit and gave me the TV for free because it had "gone off-line" as he put it.
Well, the picture is dreadful and hardly visible. No amount of adjusting the colour, contrast or brightness makes the slightest improvement; they just affect the screen luminence, as it were, without improving the picture.
The three colour tubes (or is it guns) inside can be adjusted (increase/decrease colour) having removed the front cover below the screen, as can the focus, but none of this improves the picture. I have also cleaned the mirror and the surface of the tubes which were very dusty - still no improvement.
I know my neighbour to be, shall we say, a dilatory sort of person e.g. when he recently stayed with us he went out for several hours leaving seven lights and two TV's switched on, and I know he used to leave his PC permanently on; so it would not surprise me if his TV had been switched on for most of its life.
Does anyone have any idea if this TV is salvageable or is it beyond economic help. Thanks: