The item I have owned longest is a Heathkit RF-1U signal generator which I assembled from a kit more than forty years ago (that makes me feel old!
). It spent many years in my parents' loft but I recovered it when I set up my workshop about fifteen years ago. Apart from fitting a 13A plugtop as it originally used a two pin 5A plug (my parents' home didn't have such new-fangled things like ring mains), it required no other attention.
Edward