Monitor failing

[Pi]

I have a 17" monitor, Hitachi MC611ET. It has always been the best piece of my computer, at least in the last 8 years. Some months ago, it started doing strange things. In the first 30-60 minutes in the morning, when the monitor is still "cold", I can see these "waves" going up and down. They're irregular and barely detectable, it's as if the intensity (not the image) fades for a nanosecond, and this wave of shade goes up and down at random. It might happen for 5 minutes now, then stop, then another minute, and so on until the monitor has been on for a while.

But in the last 3 months, there's something more. I think it started because someone lent me his PS2 with a VGA-Box, so I could play the PS2 with my monitor. After playing for like 4-5 weeks, after changing from the PS2 view to the computer view, the monitor would show the image with a smaller width than the settings I've stored. Once I returned the PS2, the problem persisted. At first it was after coming back to my desktop resolution from a game (e.g. MAME), but now it happens any time. I tried changing the refresh rate but nothing. What really shows me that the monitor is failing is that most of the times, it restores the width if I punch the side or the top of the monitor. But I'm not doing that anymore, because when I do it, now I can hear a piece moving inside!

Advices? Is it easily fixable, or is it damaged beyond repair? Am I losing my monitor?