Hey internet, just so you all know, it is VERY common, essentially universal, to secure large components that could be susceptible to vibration on a circuit board with GLUE.
That includes electrolytic capacitors. So, while they can indeed go bad and even leak from time to time, I think that all lot of people might be mistaking this glue for "leaked caps" and then replacing caps that are fine. I am not in favour of shotgunning repairs, especially for amateurs, as there is a high risk of creating new issues. That includes wholesale replacement of capacitors.
That being said, electrolytic caps can and do dry out and cause problems. Identify the symptoms and proceed logically, don't replace every cap just because they were glued on when the machine was built.
A bad cap can LOOK FINE, or it will bulge a bit or push out the bottom, etc...
Just sitting by the fireside building on our vast knowledge....