Try our re-instated info resource - "Aladdin's Cave" (Main menu)- sorry it's taken so long to fix
Have you undone the retaining ring, it's a left hand thread? The downloadable manual here will show you how to remove it.You will need the tool or make one similar, use the search facility here it's come up loads of times.Page 51of my 500 rebuild link below has the page from the parts book.
Should have asked you could have borrowed mine!.Make one from nice thick plate with a handle welded on then cap screws to fit the holes in retainer fitted into carefully drilled holes
They are usually very tight. I made a tool which did work, I had a length of square section steel and drilled 2 holes through at the exact distance of 2 of the holes on the retainer. Then found 2 bolts, 6 mm if I recall, passed through the bar then a nut to keep it solid but leaving enough thread to fit in the holes. Not as good as a 4 hole tool but did work for me.
I understand your problem Neil and the material Bryan suggested is easily obtainable. Do you have a 'Men's Shed' in your area? (Try searching ukmsa - UK men's shed association). They might have a suitable piece of scrap and if you took along the wheel they could accurately measure hole diameter and spacing to cobble something together. These sheds are all over the Country (in fact, the World) where folk get together for a yarn and a cuppa and many have good facilities and expertise. Don't forget to tell them wether it's left or right hand thread!Just a thought,Ian