Front Element Removal: 400mm f/5.6 L.

Does anyone happen to know how to remove the front element from the 400mm f/5.6 L? I can find loads of information on dismantling all manner of lenses, but not this one.

I know what the advice is going to be, but I would still like to know how it is done!

If it helps any, found a parts catalog here is that the one?

from the cross-section diagram at the end, looks like could be just a circular collar (CA2-0395) on the outside of the front element that needs to be unscrewed to get the glass out.
Not sure what the correct tool would look like, probably depends on how many slots are on the collar - obviously you'd be doing this at your own risk!

That's the one!

Thanks for that. I'll be able to work out where to hammer it to get the front off now!

Take video - it would be funny to see a hammer-drill involved...

And remember,if it doesn't shift you haven't used a big enough hammer.

Don't worry I've definitely got the right hammer for this job!

Before-and-after photos?