My friend's 1920s Mortise locks have a "3" stamped on the outside cover. However, both of these keys (the 2-bit and the 3-bit) work. In fact, the 2-bit key (the one without the notch) actually seems to work better. "3" may have been the production line, or something, for all I know. Took about as long as it said to get here, but you can't beat the price! Someone wrote something about the head breaking off. The original keys to your Mortise lock were probably iron. These are brass-plated zinc, and not quite as strong. I'm sure that it would be very easy to break the heads off on a rusty, or otherwise stuck, lock or bolt. That's why it is IMPORTANT that you prepare the bolts and/or locks by cleaning and oiling them: Part I: Dis-assembly (only 3 steps!) 1. Remove the door knobs. 2. Remove the face plate (the metal plate where door meets the wall, and where the latch and bolt are). 3. Remove the entire unit from the door. That's it! Do not take the box itself apart by removing any more screws until you've tried everything else. The setup inside the box is very simple, but there are at least 2 springs in there that can easily pop out and get lost. Part II: Clean the bolt 1. Spray the bolt (only the bolt, for now) with some general-use oil, such as WD-40. 2. Wipe clean with a clean rag. Repeat, or scrub, if necessary. Part III: Oil the bolt and lock 1. Spray the bolt again with a quick shot of the same oil. 2. Wipe it down with another clean rag, leaving a light coating of oil on the bolt (if it looks like any of the oil could eventually drip off, you've left too much) 3. Make a very quick shot, or burst, of the same oil, inside and upwards of where the key will go. You're done! Part IV: Reassemble and test 1. Reverse the very first three steps (in other words, put it all back the way it was). 2. With the door open, gently try using the keys. I say, "with the door open," just in case the bolt isn't lined up with its place in the wall. Hopefully, the the key problem is solved! Problems: If the keys fail to work with the door open, it could be any of at least 3 things: a.) There is still something blocking or gumming up the bolt. Repeat Parts I through IV. b.) There is something wrong inside the box I said to not take apart. Have someone who is mechanically inclined take it apart and look at it. c.) They aren't the right keys, but you are now ready for when you DO find the right key(s)! Good luck!
