One thing I did notice is that the valve diameter is smaller than the 40mm opening. Here's a pic to explain.
I kinda think it's supposed to be that way, but then again, this is the first wg I've ever taken apart.
The other little thing I noticed was that the back part of the valve where it's threaded looks like it should screw into the metal cup and then the bolt and washer on top of that. It looks like there used to be threads in the opening of the metal cup, but they are pretty much shot. Here's a picture of that as well.
Threaded Mode