I've had a problem with my Gateway monitor that's been going on for 5 years or something now which gets fixed by nudging it

This is called vertical foldover or collapse and usually when you have an issue like this that is fixed by hitting it, it usually means there is a cracked solder joint on the vertical deflection chip.

It worked if I propped it up cause that would flex the PCB enough for the cracked joints to connect and I played all of Dark Souls like this, sometimes the screen would collapse in the middle of a boss fight and I would get fuckin slaughtered cause Dark Souls has no pause. This was my late mom's monitor that she had for her Windows XP computer and I salvaged it from her old house when she moved out. I played so much Sims and Simpsons Hit and Run on this monitor. And it's time to properly fix it.
I opened up the case and reflowed all the cracked joints I found as well as the pins of the vertical deflection IC and that got it fixed at last. I'm so happy about that because this is such a good monitor.
@JikissGamer My 486 monitor has a problem where the image shakes (a lot) until it's warmed up.
@Vyothric That could be caused by aging capacitors, I need to recap several of my monitors and TVs cause they're getting old.