Hi Bert,
In old test equipment, just as with old radios, the best policy is to assume the electrolytics are bad and replace them. For a temporary test, you can parallel the old electrolytics with new ones (be sure to observe proper polarity), either by spot-soldering them or using alligator clips. If operation improves then go ahead and install them permanently, being sure to remove the old electrolytics from the circuit.
Poston
:I recently picked up an old PACO signal generator, with original electrolytics. It does have some hum and when using the probe there is quite a bit of static/noise when I touch various grids and plates of radio circuit. How can I determine if electrolytics should be replaced?