When I look at catalogs for electrolytic capacitors I get rather overwhelmed by all the different specs until I just give up. Whats the basic spec to look for with replacing the cathode caps and the filter caps? I have a Gibson Scout with a gawd awful hum with scratchy pots. Other than that it sounds really good. All these caps are 20 uF at assorted voltages.

A meter would show if they were shorted, right? If its a case of true open then the checker you spoke of is needed.

I have some small caps that look like resistors but green in color. A couple of values I recall is 10 pf and 100 pf. The cap check on my meter works well with most caps I try with it but these small resistor looking ones dont check. Ive tried using the resistance range but Im not sure if these can be checked. Any insight on testing these type caps would be wonderful.