Removing 300tdi auto box shifter

I'm trying to remove the shifter handle from my auto box but have hit a snag. I prised out the top cap/removed the 'C' clip/removed the spacer/slid out the spring loaded button/prised out the spring and it's here where the Haynes manual says 'prise out the locking clip then unscrew the retaining nut'. Well I couldn't see any type of locking clip so just removed the locking nut. Having done this the knob slides up about 25mm and stops. It's a very definite 'mechanical' type of stop, as if it's hitting something that prevents it coming up any further. What am I missing or doing wrong? There are no more clips that I can see. Any advice would be most welcome.