How can I test a starter?

Looks like a re-occurring thread topic lately, but I'm having starting problems. I charged my batteries and both read 12.6V, but when I go to start the starter makes the clicking noise. I'd say a month ago I could at least get it to engage and turn the engine over, but wouldn't start. I'm tempted to just go get new batteries in case they've lost some of their CCA's over time, but I'd also like to know how to jump or test the starter to see if it's good or not.

If you have a burned up starter solenoid there's nothing you can do to get it to turn over with the exception of tapping it with a hammer...and that's an extremely short term fix. You'd have to replace the contacts in the solenoid to make it work again. I've done that with several of them and it's worked great.

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Put your volt meter on each battery while cranking. If the battery voltage drops below 10 volts, the battery is toast. How old are these batteries? Can you see any bulging of the sides? Feel with your hand. Any bulging at all is bad. Each battery can be tested individually.