Just an update....I actually got them apart per the email below:
Hi there.
It's easy.
The main shaft has a thread at the top. The shroud that you want to paint and
the top mounting both screw onto this shaft.
Secure the top aluminium mounting in a vice and simply turn the shroud which
will release the top mounting. If it's tight use a pair of grips, but wrap a
cloth round it first and hold the grips at the top so you don't knock it out of
shape.
Then the shroud also has to be screwed off the thread. This part can some times
be a bit tricky because the shroud and the shaft want to turn together, so you
may have to grip it with some pliers.
Hope this helps.
Stu