He says that it still works, but it doesn't look too pretty. We have discussed the possibility of straightening out the thread, but in my experience those projects never work out really well.
So I offered that I could try to make a new screw for him on the lathe.
It greatly helps that the original is made out of brass, because turning stuff in brass is kind of like whittling away in balsa wood.
What doesn't help the project is that there seems to be comparatively little information on this particular screw regarding what type of thread it really is.
I compared Brians measurements with what information I could find, and I landed on a 5/16" 20 TPI (this time it is threads per inch, not teeth per inch as in a saw).
My next problem was that I have no idea if Stanley used the Whitworth system of 55 degrees threads, or if they used 60 degrees like metric standard thread.
A bit more searching on the Internet, and I decided that the American industries from a very early point liked the idea of having 60 degrees threads.
So armored with this information, I cranked up the lathe and made a screw.
Since I am in the middle of the North Sea, and the plane needing the screw is in Munich, I can't tell if it was a success or not. We'll have to wait until I get home and can send the screw for actual testing.
But personally I think the screw looks nice, and I got to practice cutting threads on a lathe so that makes it a nice little project.
Stanley No 12 blade holding screw.