My plug pack for my 1976 scientific calculator died. I have used that calculator and the original plug pack for 44 years. I opened it up and the transformer had gone open. It did not upset me - these linear plug pack power supplies waste power and are much less efficient than a modern SMPS, so I changed it to a 5V SMPS regulated output plug pack and transplanted the DC connector.
Out of curiosity, I tested the 1000uF filtering capacitor which was "Bellcon" brand. I could not believe that after 44 years, the cap measured 1269 uF.
It was definitely not made in China, because back then China exported nothing. I suspect the capacitor may have been made in Taiwan. I could find nothing on Bellcon brand, except a few rash statements on blogs by people saying Bellcon are rubbish, without any backup evidence.
I have seen many crappy electrolytic capacitors in my day - especially in cheapo radios where they are used for DC blocking in audio output stages and in TV sets.
But this capacitor was impressive. The body was in perfect condition. Why didn't the electrolyte dry up at least a bit in all those years?