Can a S&G lock slip it's combination due to shock?

[QuietCanuck]

Can anyone tell me if it is possible for a Group 2 Sargent and Greenleaf R6700 combination lock to slip it's combination if jolted?
I ask because I was recently given a used safe, and when it was loaded into the back of a pickup truck, it slammed down 1 foot onto it's back in the truck bed, then driven 20 miles, and once at home it would not unlock with the combination I was given. Since the door was already open I removed the back of the S&G lock case and found that to open it one of the numbers had to be dialed off by 2 digits, and another off by one digit. So either the person who wrote the combination wrote it incorrectly, or the fly moved relative to the wheel due to the impact it took moving the safe.
I am not familiar with the inner workings of an S&G lock as I have not taken it apart yet or even removed the spline key, but will if it seems prudent to check the wheels etc.
So, can anyone tell me if the combination slipping is not unexpected with an impact?

[Squelchtone]

Can anyone tell me if it is possible for a Group 2 Sargent and Greenleaf R6700 combination lock to slip it's combination if jolted?
I ask because I was recently given a used safe, and when it was loaded into the back of a pickup truck, it slammed down 1 foot onto it's back in the truck bed, then driven 20 miles, and once at home it would not unlock with the combination I was given. Since the door was already open I removed the back of the S&G lock case and found that to open it one of the numbers had to be dialed off by 2 digits, and another off by one digit. So either the person who wrote the combination wrote it incorrectly, or the fly moved relative to the wheel due to the impact it took moving the safe.
I am not familiar with the inner workings of an S&G lock as I have not taken it apart yet or even removed the spline key, but will if it seems prudent to check the wheels etc.
So, can anyone tell me if the combination slipping is not unexpected with an impact?

Were you just given the safe combo on a piece of paper or did you dial it to the correct numbers prior to loading the safe? It's possible the combo was written down, and to the old owner, what they were dialing by standing over or in front of the safe looked like the numbers on the paper, but maybe from their angle it was a few off to what you found actually opens the lock. Someone else here will have to chime in if the fall would make a difference. I know I once went out to change a combo on a mesh gear safe and the inner numbers did not match the outer dial numbers, so I had to fudge the inside mesh in order to make the combo be what the owner requested. (can't tell them that their combo is 64 and a half if they asked for 66 to be one of the numbers =)

thanks for sharing your story,
Squelchtone

[shadow11612]

First, you said it is a 6700, but is it a 6730, 6731, or 6741. The reason I am asking is that the 6741 has a 1.25 number tolerance (the 30 and 30 have a 1/2 number tolerance). If it is a 6741, then as Squelchtone stated, then at what angle you are looking at the dial can make a difference, especially if you have a open face dial, vice a top view or "spy proof" dial.

Now can a safe change it's combination due to a fall or shock. That answer is yes. A key change wheel has an inner and outer hub, with very small teeth that mesh together. These hubs can slip, but more often it happens to older locks that have worn teeth.

In my former life, we had small one drawer tactical field safes. These things would to be thrown around, in and out of our Humvees, and basically dropped and beat up. And on occasion we would have a lock that changed combination on us. We even had a matrix sheet that you would fill out. We would take the original combination, add or subtract 2-3 numbers to each, and the matrix would show all the possible combinations. 99% percent of the time we would get it open this way.

I would throw this out there too. If the combination has been changed recently, someone could have used the wrong change key. Using the wrong change key could cause the hubs on the discs to work improperly. Slim chance, but possible.

[QuietCanuck]

Thanks Squelchtone and Shadow for your replies. To answer your questions:
Squelchtone:
Yes, I simply received the combination on a piece of paper, and I had never dialed the combination myself. Therefore yes, it is entirely possible that she had always dialed it to a slightly off number based on where she stood and never noticed the difference. Another possibility was that they wrote down that one number wrong (and that the other marginally wrong number was just close enough to work for them but with little margin of error so they did not know it was off). I believe the lock was at least functioning properly at the time because she said they locked it every night and opened it every morning (it was used by a business).

Shadow:
I am not certain of the model number as I do not know how to properly identify them, but from what I have read it does appear to be a 6741 based on the fact that the back cover has an "R6700" cast into it and that the material of the lever is not brass (two identifying features I read about). The sticker on it says "Group 2" and "No K xxxxxx" (which I assume is a serial number). The lever will indeed still drop into the wheel with a total variance of 2.5 digits (so it is +/-1.25) which would further support the 6741 belief.

Thanks for the information that indeed a combination can slip. When it does slip based on a shock, does it damage the teeth and require an overhaul, or did you just reset the combination and continue to use the lock?

[camelgd]

Don't have much to say, as squelchtone and others said it quite well. One possible cause of the combo apparent slip could be changing the combo with the back cover off. This causes two problems a) an unsteady hand holding the change key can cause a variance in the combo; b) The wheels could be left partially unlocked, which is a real disaster in the making. Also. LaGard was notorious in their earlier days of combo slippage during normal use. In corporating new materials in the wheels supposedly cured the problem.
Al D. Camelgd

[shadow11612]

Thanks for the information that indeed a combination can slip. When it does slip based on a shock, does it damage the teeth and require an overhaul, or did you just reset the combination and continue to use the lock?

The teeth and inner hub can wear down over time, and possibly the shock of a drop could accelerate the wear. But I would not worry about it to much. The few times I have seen it become a problem is on a lock that has the combination changed often, like every couple of months, and the wear takes years. There are S&G locks that are decades old and still work fine.

If you are really worried about it, a new 6700 series lock, and you would only need the lock itself not the dial or ring, runs about $65-75. You could replace the wheel packs, but they run about the same price as the entire lock body, and it would be easier to just replace the lock body instead of installing the wheel pack.

[dls]

The thing i would suspect is that the lock is worn or the bezel which is attached to the door is loose or has turned slightly, this is possible if the dial is lockable and was forced while locked if the screws where not properly tightend.

[QuietCanuck]

Thanks all for your suggestions/tips.

Due to the concern over the possibility of the teeth in the wheel being worn and slipping again, I disassembled the lock and found the teeth to be in great shape (no wear as I can see).
The dial's bezel feels quite secure and does not slip when a reasonably high force is applied by hand. Of course during the moving of the safe it is always possible that an "unreasonable" force was applied, so this possibility can not be completely eliminated.
After seeing all this, my guess is that it did not slip after all but was likely what Squelchtone said in that the combo was viewed off angle or was written down wrong.

Regardless, I have had a fascination with locks since childhood and this was a great learning experience.

To make sure I reassemble the lock correctly, I have one last question. I have completely cleaned all the parts with alcohol, and already have an S&G recommended lubricant on hand (Molycoat Gn Paste). The S&G Lock Guide shows the lubrication points in the lock case (such as the wheel post and the boltway surfaces), but does not mention applying any lubricant to the wheel fly or the spacer/isolation rings. I assume I can lubricate the spacer/isolation rings as they will get lubricant on them over time anyway (it will travel from the wheel post as the lock is operated over time), but should I apply a light coat of lubrication to the wheel fly, or just leave them dry?

[shadow11612]

I would just leave them dry. The book answer is that they are self lubricating, and I will not argue that they are or are not, but I have never lubricated any other part than those specified by S&G.

I have heard 2 arguments on the topic. Both relate to having a stuck fly wheel. Some old safe guys swear that the reason a fly becomes stuck is due to lack of lubrication. Others will tell you that lubrication attracts debris, which then causes a stuck fly situation. I can say from my experience that I have never lubed the flys, and I have never had a stuck fly wheel.

It is my opinion, that if a safe lock is serviced regularly, the parts are inspected for wear, and replaced when necessary.

[cledry]

Don't lubricate anywhere where it doesn't say to, this means the wheels. It is asking for trouble. One other thing to check is the spline key, make sure it is tight and that the drive wheel has no movement when the dial is held firm. If there is any spline key play try a slight bend in it and tap it back into place.

[QuietCanuck]

Here is an update for those who read this in the future and wonder what the outcome was:

I did as recommended by everyone here and left the wheel flys dry (it appears that lube migrates to the ring part of the fly regardless, but I did not deliberately apply any to the fly's ring or fly tab itself).
As for the rest of the lock, I lubed the S&G specified points with the same grease S&G uses at their factory (AeroShell 22) mixed with a small amount of S&G's specified optional lubricant (Molykoat Gn Paste, in order to get some solid lubricant to the surfaces as well), and applied the mix sparingly as S&G states. I reassembled it all, tested it, and changed the combination without event. It has now been operating great for the last 2 months (very smooth and consistent), so thanks again for everyone's help.