If you post a photo, I can probably help you with manufacturer/age/value/etc.

As far as the lock working properly, I can certainly give you advice. Sometimes I can figure things out based on a description of what is happening, but nothing beats seeing what you're working with in person. Having a local guy take a look at it shouldn't cost anywhere near $500, unless you live in the middle of nowhere.

Two possibilities come to mind immediately.

a) two of the three tumblers are actually set to the same number. They'd have to be consecutive, like 1st & 2nd, or 2nd & 3rd.... couldn't be 1st & 3rd. Most people who don't know any better will add an "extra number" to a combination, but that last number is actually where the dial stops upon opening, and will always be that number even if the combo is changed, as there's no tumbler to change that corresponds to the full-open bolt-withdrawn position and the last number you see on the dial before you turn the door-bolt handle and open the door.

Depending on brand (and if the dial is splined properly to match lock handing) all currently made locks will stop upon full lock-bolt retraction somewhere between 85 & 95 on the dial. That is NOT part of the combo... no matter what the combo is, that number will never change and is the same (or very close) on ALL locks of that brand & model. IOW, everybody's safe with the same brand/model lock ends with the same number on the dial before you open the door. It's the 3, or 4, numbers that are dialed before the dial stops that are the actual combo. My point is, if the previous owner gave you 3 numbers, and he (or someone prior to him) had 2 consecutive tumblers set to the same digits, the 3rd number he gave you may be the stopping point when the bolt is retracted, and not a real combo number. The reason for setting two tumblers to same digits is to speed up the dialing process... it allows "skipping" a step in the dialing procedure.

b.) Only applies to old safes that haven't been used regularly... if the safe sat for a long time without being used, and the lock was in the open position all this time, if it was in a damp environment (like a basement), it's possible two tumblers corroded or rusted together. The tumblers may be set to differant digits, but because they're "fused" together, they act as one. But to act as one, they would've had to be fused together in the open position. This would mean one less step in the dialing process also, just like "a)" above.

It sounds to me like you need a combo change and inspection/cleaning of the lock (do NOT oil it!). This shouldn't be too expensive. I charge $25-40, plus trip charge, to change a safe combo. Trip charge is typically figured by mileage, so don't call someone 100 miles away.

If you've taken the cover off the lock, count the round disks in the lock. One of them is the driver wheel, and is directly threaded onto (and splined so it can't unthread) the dial spindle. All others are the tumblers. There should be a number in the combo for each tumbler in the lock (plus the stop number). The driver wheel will have a differant shaped cut-out on it's perimeter than the others.. it's shaped to accept the "hook" on the lock bolt, because after the tumblers are aligned, the driver "hooks onto" the lock bolt and pulls it inward on your last turn of the dial... when bolt is fully withdrawn, dial cannot move any further because it's been "hooked" to the bolt via the driver wheel. All bolts stop at the same place, ergo, all dials (same brand & model) stop on the same number.

Depending on lock brand/type/age, the driver wheel may be at the back or the front of the stack of tumblers. You shouldn't remove, nor mess with, the driver wheel. The spline keys can be broken off easily. No need to, unless dial's indexing ring is loose, in which case the dial must be removed to access dial ring screws for tightening.

The tumblers may be mounted in the lock body itself, or mounted on the back cover. If the tumblers have numbers and little index lines around the center where the two piece tumblers meet, these are known as "hand change". You can read the current settings on the tumblers themselves, and change them by seperating the two parts of the tumbler wheels (they snap apart) and put them back together on a differant number setting. They have very small serations that look like gear-teeth to prevent them from slipping. They're not actually gears because they do not move, but they look like gears.

If the tumblers have no digits visibly stamped on them, and they're mounted in the lock body and not on the cover, and the cover plate has a small, odd-shaped opening in it... these are known as "key change" tumblers, and a special "key" (actually closer to an allen wrench in reality) is needed to change the combo. Which key is needed depends on which brand & model lock you have. I have about 18-20 differant "keys", some I've owned for 25 years and never used. Others I use so often they get worn out in a few years.... (specifically for current models of Sargent & Greenleaf and LaGard locks.. I carry one of each change-key in my pocket ).

A picture of the lock body with the cover off and held next to the lock body, would help identify the lock. Also a pic of the dial. Certain locks have certain "quirks".

Never got the photos.

That's me. I got the pics, I'm pretty sure you got my replies about the missing halves of the hand-change tumblers, yes?

BTW... I rummaged through my "collection" of used safe parts that I've accumulated over 25+ years in the lock/safe business, and just as I thought, I don't have anything that will work. I do "scavenge" old safes occasionally, but when I do get obsolete parts, they don't last very long before someone buys them from me. If I come across any, you're 1st on my "waiting" list.