[Arran]

A lot of people think an ESR tester will tell them whether a cap is good but point in fact they will only tell you which ones are definitely bad. ESR meters are fine in newer solid state electronics where you are only dealing with low voltages of between 6, 12, and 30 VDC, but they give false readings on paper capacitors. A paper cap will often test fine on 9 volts but since it's supposed to test fine at 400-630 volts it really isn't that useful of a test. Eico, Heathkit, B & K, Precision, Solar, RCA, and an number of others made resistance capacitance bridge testers that put high voltage across whatever you are testing, though 400 VDC is usually the maximum. I've made a habit of testing all replacement caps on a bridge before I install them, I've had some NOS surplus caps before that were not really the best, the worst ones are Hunt capacitors.
Regards
Arran