…..OK, so I'm still building up the courage to take a set apart…..

The motion adjuster has stopped working – it winds the forks down (they're at 100mm now) but turning the other way to incrase length just undoes the black holder at the top. Do I really need to MTFU and strip these things apart, or is there an easier fix to get them to go back to full length allowing me to put the "maintenance" moment off for a bit longer? I'm fairly convinced that my hamfisted attempts at stripping a set of forks will reveal a wormhole that will cause the universe to end or something.

remove teh central screw that holds it on – clean the dial its self and the BBs under the cap – grease and all should be good again

When you say "The black holder at the top" do you mean the air valve cap? If so, sounds like it's just lost the circlip that sits on top of the uturn adjuster.

It's the piece directly under the travel adjuster – in effect, the base of the U "handle".

Thanks for the advice, gents

Motion control is the damper, you're talking about uturn.

Remove the adjuster and clean/check the three springs and ball bearings are there

Finally got my courage together, M'dTFU at the weekend and took it to bits. Thanks for the tips about the springs and ball bearings – they were corroded up, obviously water had got in. Replaced oil, cleaned foam washers, re-greased ball bearings, it wasn't too hard, I just took my time. Forks work perfectly now, I even adjusted the air pressures! I now think of course that I know all about forks….!