Darren you seem to be missing the ball races and locking ring. The ring has two holes in it for a special tool to locate for tightening it up, but I used a small punch on mine. If you send that picture to Welbike UK I'm sure they'll know what parts you need.
If you google Rob Van Meel, he sells reprint manuals and parts lists (unfortunately the welbike lists are not illustrated). Also buy a copy of 'From Welbike to Corgi' Revised edition by Peter Miller. I can give you his email if you PM me. Ron