Here is a call we often get that drives me crazy: “My safe quit working today and I can’t get it open. The lock started acting up about four months ago and kept getting worse, but now it won’t open at all.” The safe now needs to be drilled open and they complain about a bill of $300 to $400.
The most common reason a combination lock goes bad gradually, and then fails completely, is a loose “spline key”. When you turn the dial on a good combination lock a spindle transfers that movement to the lock body which is mounted on the inside of the door. Three or four wheels and some other parts are held in place on the spindle by a tiny L-shaped spline key, pictured on left. The other photo shows the inside of a Group 2 lock. At the center of the “drive wheel” is the spindle. It is grooved to hold the spline key (here pointing to 10:00) that in turn unites the wheels to the spindle.
When the spline key gets loose the wheels move, so they are no longer in sync with the dial. The lock will not open consistently even when dialed accurately. Keep trying to use the lock and the spline key will loosen up more, until it hits the inside of the lock cover or it falls out completely. In either case you are locked out of your safe.
When your safe acts up, don’t put it off. Avoid paying to drill it open by calling a competent safe technician immediately when you have problems.