In the last 20 or so years, in about 95% of my repairs the problem were always bad electrolytic capacitors. There are people who claim the capacitor plague ended in 2007, but it is 2020 and I still routinely find bulged and/or leaking electrolytic capacitors in equipment build well beyond 2007.
A bulged or a leaking electrolytic capacitor is the best thing that can happen to you. Just look around, see the damaged capacitor and replace it. Easy. But... how to find a bad capacitor still not bulged? Use a capacitor tester and measure its ESR. This is the most logical response I should obtain. It was also my first idea. And I did it.