Hi Kevin,
Some insurance companies will stipulate that you must have british standard locks on your doors, it is important that you check your own insurance documents to confirm if you need to upgrade your locks. I would suggest taking a look at...
Yep undo the four screws and move the keep slightly. don't move it too far too soon or you'll end up with a howling wind blowing up the side of the door, or a door rattle in the wind.
You may need to cut out some move wood depending on the movement needed but don't get to carried away or you...
OK i would suggest that you have a Era Fortress classic 2.5 sashlock.
If when you move the handle the latch operates and returns as it should the first plan of attack should be to move the keep as was suggested earlier. If the handle does not operate the latch remove the handle from one side...
What is the measurement from the edge of the door to the centre of the key hole?
Does it say Union on the face plate (the brass rectangle on the edge of the door)
What is the size of the faceplate? 25mm x ...?
Couldn't agree more.!
It will be far simpler for you to replace the lock than it is to try and get a part and fix it. There are loads of web sites out there offering on line live support. They will talk you through the process of finding the correct replacement. From there simply shop around...