I'm in my 24th year with my '2-wire' F-2B, no problems!
I did replace all my electrolytic caps a few years ago (just to be safe, it was still working fine), and I suggest you do the same if yours is over 15 years old and never been recapped.
There is some foam padding support under the large filter caps which deteriorates and starts to crumble and get mushy when it gets very old. This foam support should also be replaced if it shows these signs of deterioration.
(Message edited by gblick on March 30, 2006)