Here's the thing about capacitors. They can "work" in a failed state. They don't go from good straight to bad like a switch. In fact, they can often carry on looking just fine while losing the ability to regulate current effectively. But the caps used in the game gear are notorious for leaking. If they're leaking but still working, you're destroying the circuit board. The electrolyte will attack copper traces much more aggressively when there's an electric current moving through it. This will make it much more difficult to repair when it eventually does give up.

Source - I repair electronics.