I find it interesting that they only had to replace three capacitors in one power supply. Don't electrolytic capacitors (the most commonly used type) have a limited lifespan because of electrolyte evaporation? Naively, I would have expected that every single capacitor in the system would need to be replaced.
I work on machines that are usually 20-30 years old if not more and I pretty much have to replace all the capacitors on them due to age. They tend to dry out, crack, or balloon up.
Even when correctly manufactured they do have crappy lifespans, relative to most other things they share the board with. I wouldn't count on most wet capacitors lasting more than 10 years, even when handled with kid gloves. I've got plenty of things running with capacitors well beyond that age, but they were demoted from production to testing or nice-to-haves.
The lifespan of a electrolytic capacitor is strongly influenced by temperature[0]. A 10C increase in temperature can lead to a 50% reduction in lifetime, so its highly likely that the power supply that caps failed was slightly hotter during operation than the others.
As other posts have mentioned, its mainly due to a bad batch that was produced in the late 90s. I have 4 30-40 year old musical instruments that are on their original caps and work just great.
