how to recondition capacitors ?

Hi,

I have a few 10,000uF,50V caps from old printers and wanted to make
sure they were up to snuff before putting them in service.

I've read that one should reformat them or recondition them but I
couldn't anything regarding how to do it.

also, any tests to do to make sure they would be good for a powe
supply ?

any ideas ?

Dave