Sealed batteries can't be gravity checked. If you've got a vehicle handy to install the battery into, try spinning the starter for 15 seconds with the ignition disabled so it won't start. After that time, while still cranking, the battery terminal voltage of a good battery shouldn't drop much below 10 volts. It's a quick and dirty shade tree load test, but it works pretty well.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!