I have this exterior door and I would like to replace the aluminum threshold. I assume this is the original threshold and am wondering that is the best way to take out the old threshold. Original floor is terrazo as you can see on the outside. The inside is tiled over the terrazo so it's a bit higher. How is the threshold connected to the door jamb? Is it nailed/screwed from the bottom up into the end of the jamb? Is so then there is very little chance of removing it without tearing up the jamb bottom? I do not see any screw holes, so I don't think it's screwed into the concrete floor. If I take an angle grinder with a metal blade and cut across the existing threshold, can I wiggle and finesse out each half of the threshold without damaging the wood jamb?

I have an exterior wood door that has one of those "aluminum door bottom" with a slot for a vinyl insert. The old vinyl insert has totally disintegrated. I looked at various door options at the local big box store, and found a vinyl insert that works with the door bottom, which is this one. However, it didn't work because this insert is very thick and the gap between the bottom of the aluminum slot and the top of the aluminum threshold is really small. Here is a picture with dimensions. What other options do I have to bridge that small gap? Besides replacing the door and threshold which is not practical at this point.