problems with the locking mechanism

Thanks for posting. Can you elaborate on what the problem is? Is it that the mortise hooks aren't extending properly, or is it that they aren't connecting to the keeper?

If it's the latter, then it may be just a matter of adjusting the mortise hooks. You'll see a small slotted screw on top of the top hook and below the bottom hook. These are adjustment screws. If you turn them, you could get the hooks to extend enough to latch onto the keeper.

If the mortise lock is just malfunctioning, then you need a new one. I recommend our 82-260 as a replacement. This looks like it'd be a good match for yours.

Not a problem! Definitely try adjusting first, since that's free of charge. If you adjusted the hooks and that didn't work, though, let me know. We sell the 82-249 keeper, which looks like a match for your original. I can at least confirm that it is compatible with our 82-260 mortise, which I still suspect is what you have installed right now.