[morzh]

What he refers to is called "reforming". Yes it is a valid procedure but only for those caps that did not go all dry or crystallized inside. Doing it to an old radio is not a great idea. And if done to a radio with caps from, say, 70-s that still could be reformed, the radio should never be left unattended, so much for 24hrs.

And this only works for electrolytics. Not paper caps.

So, in short - don't do that, change the caps.