The company where I work has a large Mosler safe (it’s about the same size as my storage shed). The handle won’t move so we can’t lock it even though the dial works and we can run the combination. I have tried to reach the Mosler company and discovered that they are out of business. Any suggestions for what I should do next?
Bit of a boilerplate answer, sorry, but yes; you should call a locksmith.
Mosler went down the drain about 5 years ago, but their safes are well known to anybody with a safe and vault background. By “handle won’t move” I assume you’re talking about the handle used to throw and retract the bolts. I’m going to presume that the bolts are presently extended, because you can dial the combination. That being said, the bolts have to be fully extended, as partial drag on the combination lock can prevent complete retraction of the lock bolt, which then interferes with retracting the main boltwork.
When you first turn the combination dial, do you feel a drag, as if you’re winding something? If so, the combination lock is fitted with a time delay, which may be 15 or more minutes. In that scenario, you dial the combination normally, set an egg timer, and at the end of 15 minutes retract the lock bolt and then throw the main boltwork. There is only a three minute window to retract the lock bolt, though.
On the subject of time delays and related mechanisms, many large chests have two or three movement time delays, and a broken mainspring or other malfunction in the delay case can preclude bolt retraction. Swing the door open and look for a rectangular box ~6" or 8" wide x ~4" or 5" high. The cover should be partially clear, exposing the winding ports, faces of the movements, and their individual indicators. Are one or more of the movements down below zero?
If it isn’t bolt bind, and isn’t time delay equipped, then there is a problem inside the boltwork requiring the services of a safe and vault technician.
danceswithcats-field technician/installation supervisor (former) for Inter Innovation LeFebure, who went down the drain a year or so before Mosler. 
We had an old safe do that. We sprayed it with WD-40 and whacked it with a hammer. It worked, but I suspect that danceswithcats is giving a much better answer than I am. 
Don’t whack a safe too hard! A lot of good safes, and Mosler certainly is a “good” safe, have what’s called a glass relocker. It’s a piece of tempered glass in the locking mechanism, that if broken, fires the main bolts into a **permanently ** locked state.
Normally, a glass relocker is only triggered by physical attempts to defeat the main lock by methods such as drilling or cutting with a torch or lance, but excessive hammering could also break it.
IANA Anything relevant, but some obvious advice. Before you start experimenting with it, empty it. Don’t compound the problem with having trapped valuables.
Another thing. If the door is infact open, DON’T CLOSE IT. It’ll be alot easier for a locksmith to work on an open door then a closed one. Ask me how I know that.
Yes, but wouldn’t the locksmith be more motivated if s/he were working on the closed door … from the inside?
While it’s certainly “possible”, I never saw one on a Mosler, Diebold, or LeFebure safe or vault door. They have a variety of other methods to defeat forced entry. The only instance where I did encounter a glass relock sheet was a vault door manufactured by John Tann, Ltd. It was an impressive piece of engineering.
Yeah, well the one we did this to was made in 1890something. 
TANN shudder I had the misfortune of opening a TLTR30 that was locked up when moved then fell face first in the parking lot. shudder
I to have not ever seen a glass relocker on a Mosler. Glass relockers are not THAT common in the USA. excluding jewlers safes, they tend to have glass relockers.
Now Europe, glass relockers are common.
Now, if there is a box mounted to the inside of the door that say “Badger Safe Protectors device” walk away and call a professional. Badger Safe protectors contain a two or four vials of chloropicrin. Which if broken will keep you puking. It was used in WWI as a war gas.
I had an old Diabold with a Badger on it Monday, It was a safe built in the 30’s
Have fun and call a professional… if he comes out and opens the back cover to fix it take lots of pictures for me. Nothin like good ol Antique Mosler safe porn.
Osip
Well, I don’t think you’ll actually want to call them, but if you’re looking for “Mosler”, then here’s a clue as to where their assets went:
http://www.diebold.com/news/newsdisp.asp?id=2814
“October 23, 2001
DIEBOLD TO PURCHASE MOSLER ASSETS AND SERVICE
NORTH CANTON, Ohio – In a strategic move designed to better serve its existing customers and the security industry, Diebold, Incorporated (NYSE:DBD) today announced it has signed an agreement to purchase the physical and electronic security assets, currency processing, certain service and support activities, and related properties of Mosler, Incorporated for approximately $28 million.”
It really sounds like the thing is in relock or something is impeding one of the bolts. If the handle won’t rotate, then how do you know that the combo is working? If the handle won’t rotate, then it’s possible (but unlikely) that the combo has somehow slipped. If everything is working, the wheels lining up with the gate, then the handle should rotate unless there is something in the path of the bolt(s) or the lock is in relock. On an S&G lock, that’s happens when a soft metal plug melts. Don’t know about a Mosler lock. Building settlement could have wracked the door frame so the bolts don’t line up with the holes any longer.
Now that’s thinking outside the box!
No, no, no that’s thinking inside the box.
How do you know that?
I think this may call for a Thermal Lance!
(Cool - I’ve always wanted to use one…)
Hey, Osip! After checking out the innards of that Tann door, I would not want to go hard against one.
Your last line made me laugh-because I’d check out the pictures, too. Glad I’m not the only safe/vault nut on SDMB.
No. You’d have to impose a significant physical insult on a chest of the lowest UL rating to displace the cabinet/door alignment. As in, drop it on a corner from decent elevation.
I guess the same way I know you should empty the safe before trying anything on it.
True enough; just noodling. A safe that size shouldn’t have that problem. We occasionally used to have used file safes (800 pounds or so) that occasionally would show up after having been dropped in shipping (with the locking drawer propped open). No way to realign the damn things once that happens.