First off, You should not be able to hear the tumbler in a S&G Lock.
They use wheels, what you hear is the weelpack reset. I would also try dailing the numbers over or under by 1/2 to a whole # and play around with it a few times.
I am a California Licensed locksmith and have opened many safes with S&G locks on them. If you want to send me a PM I will do my best to help you, Sometimes pictures of the safe willl give me a better idea of how to open it. I am in Sacramento so its possbile I could come out and help you if needed. Safe openings are usually pretty expensive by a locksmith. I will try to help you over the pics if I can