Sad to say, from the pictures, I think that you’re right about the machining error.
Privately I was hoping that the alignment issue was confined solely to the depth stop.
Personally, I’ve not seen a Record 050 that is not machined correctly like this and it is a first for me.
What to do?
I suppose that the options are:
1 – Nothing….. sell it on or replace it.
2 – Find a machinist who’ll fill in the hole and re-drill it out correctly. This will probably be expensive.
3 – Gently ease the depth stop into line so that it is planar with the sole and use it this way. If everything else on the plane is in line, at least you’ll have a working tool. (Having said that, a lot of users don’t always bother with a depth stop. In reality, groove depths are seldom critical)
It would be interesting to see if the other hole for the T&G guide on the moving section of the body is correct – this is easy to spot. In use, the guide will only fit in one direction and it MUST be a correct fit. There is a groove down one side and when it is fully in place this groove should sit entirely over and cover the bottom edge of the moving skate. If you put a bead cutter in at this point you’ll see that the web on the left edge of the cutter is totally obscured; the edge of the guide now rides on the side of the T&G. Sometimes it needs a little shove to locate, but if this hole is a hair out it won’t fit correctly.
However if you never make T&G boards with a decorative bead, this is academic. The number of Record 050 planes out there with this bit missing…. proves that point!