Like 399 said... In regards to Electrolytic Capacitors, leakage is another important Test... Have to Test the Capacitor at the Voltage it is intended to operate at, for "Leakage". Capacitors can check "Good" using certain Meters, but in all actuality the Capacitor could be "Bad", as it leaks... Not talking about the Electrolyte Fluid is leaking, but rather Electricity... I have a Fluke 179 Digital Multi-Meter that can Test Capacitance, but I never use that feature... I don't bother to Test Capacitors, but rather just Replace them, as I deal with Vintage Equipment... It is said an Electrolytic Capacitor has a Shelf-Life of 12 Years... That is, if it is sitting on a Shelf, not being used... In usage, the Capacitor's Lifespan would be much less... Capacitors have ESR Ratings which tell you "about" how many Hours the Capacitor should last in use... As one has to remove or disconnect at least 1 Lead of the Capacitor to Test it, you are half-way to just Replacing the Capacitor with a New one, which is the best way to go... Most Electronic Failures are due to Electrolytic Capacitor failure, due to Age... DO NOT buy Capacitors sold as NOS or New Old Stock, as they are just that, OLD... In time, the Electrolyte Fluid within them Dries-Out... Everyone will do as He / She pleases when it comes to their Own Equipment, regardless... Quite often, a Single Failure of Capacitor can trigger multiple failures of Electronic Components in the Circuit... As I Own / Operate Vintage Vacuum Tube Type Equipment, I do not want to risk ruining for example, a somewhat Rare and therefore somewhat expensive Vacuum Tube Failure as a result of an Inexpensive Electrolytic Capacitor... So, it is not worth the Risk to me, to attempt to Operate Vintage Equipment with well-known Problematic Old Age Electrolytic Capacitors...
Here is one of my favorite Articles related to Capacitors... It references Radios and Old TV's, BUT the Components are the same...
http://www.antiqueradio.org/recap.htm
