I have an older (20+years) centurion safe that will not open. It has a Sargent and Greenleaf combination lock. It is a three number combination which I know. I can hear the combination working as normal when I get to the second number, but when I get to the last number and then turn it toward zero, which usually engages and unlocks the mechanism, it catches as it should, but then slips, and does not allow the handle to be turned. My thought is call a locksmith, but I wanted to reach out to see if anyone had any ideas before I do that .