Got some input from a bloke I know in the UK:
"The moving cone is moving out too far and running off the end of the pins. Definitely not right by a long way.
Needs stripdown and at least the washer taken out behind the fixed cone.
Back nut is LH thread *very important.
Fixed cone is standard RH thread, but needs to be undone with a chain wrench , and we heat by oxy-acetylene to heat and release the threads.
The people who assembled that are fuckin' idiots."
Fully agreed, here is the most competent of the assemblers below:
Quality control just isn't what it used to be: