Help: TV trouble

[Daigohji]

I fear that my faithful 24" Panasonic Quintrix CRT TV may be about to give up the ghost. I bought it back in 2001 and have had little trouble with it until now. Then yesterday I turned it on (barely a few minutes after the last time I turned it off) and the screen went bright green with several thin diagonal lines of brighter green across it. This lasted a few seconds and then the TV switched itself onto standby mode. I turned it back on: same thing. I untangled the power cable from the spaghetti junction under my table and tried plugging it directly into the wall socket instead of the usual 4-way power block: same thing.

After a few more attempts it suddenly decided to turn on properly. Only now the image is much brighter than it should be at the brightness setting it's at. I had to pull the brightness slider all the way down just to stop the blacks from looking too washed out. Also, when the on-screen image is dark, there are several thin diagonal blue lines across it, like this crude artist's impression:



This becomes less pronounced the longer the TV is left on, but fades back in periodically. Based on these symptoms, does this sound like something that could be repaired without too much expense, or is the CRT itself going?

EDIT: Removed the comment about this not happening in RGB mode, as it's got the blue lines in that now too.