I scored an older American Security safe a couple of years ago with the mechanical spin combination dial (made in 1990, can't find a model #)
If the dial comes to a stop on the last turn, it's a mechanical lock which does require professional periodic service. If the dial does not come to a stop, it's a direct entry lock, and you can service it yourself.
For those of you in the industry: What kind of regular servicing is performed and what is the recommended interval for it? What should one expect to pay for servicing, provided nothing is broken or worn?
A locksmith will check the lock, boltwork, hinges, etc. for anything abnormal. The lock will be disassembled, cleaned, lubricated, reassembled, and checked for proper function.
Most manufacturers state that the lock needs to be serviced yearly for the warranty to remain valid. In most residential uses, you're probably OK doing it every 5 years or so.
Most people do not maintain their safe, so I doubt yours has ever been serviced. Not a bad idea at this point, just to be on the safe side.
Shouldn't cost much more than $100. Look under "safes and vaults" in the yellow pages first, and if nobody is there, then try "locksmiths". I can also point you towards somebody qualified if you need me to.