White horizontal lines on 15" flat panel G4

I have white horizontal lines running across the screen of my 15" flat panel G4 i-mac (2003).
This first happened 1.5 years ago, when my apartment flooded and there was a lot of humidity in the room. The problem disappeared after a day or so.
Until now, it has only recurred once, and disappeared after a day. This time, however, the problem has persisted for a week; I have not left the computer on for longer than 5 minutes at a time since. I have not performed diagnostics of any kind, and am hesitant to play with hardware.
I would definitely appreciate any tips or suggestions.
TIA -
Jennifer

Hi Jennifer,
It is possible that you have a bit of crud on the motherboard (which is causing the graphics card circuitry to act up). This may be as a result of your earlier episode.
Given that getting to it on an iMac is a fairly involved task, as well as cleaning it, I would take it to an appropriate service centre and see whether they can give it a clean and get it working that way.
Cheers!
Karl

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