GSO Crayford Focuser Strip Down help needed

[russp]

I'm trying to strip down the focuser on my Explore Scientific 127 frac, I've found a number of online guides and some of these are pretty good - especially  http://polluxchung.com/gso_crayford_fix/

BUT 

my coarse focus knob is made up slightly differently - see attached picture and I cant work out how to get it apart further to get at the bearings - the little hole has a grub screw in it - taken that out but the brass disc with the slots wont budge even though it looks like it should unscrew to release the silver knob - have tried wd40 on it. Anyone taken one like this apart ?