I hope this is the final chapter in my Aga Saga. It was the only thing I hadn't been able to do. All the online info says 'if this doesn't work *remove the oil control valve* and clean the little slit in it with a bit of paper.
Nowhere was there any info on *how* to remove the f****ng thing. Mine came partially out and then simply stuck.
I eventually tried pulling and unscrewing with some force, and that did the trick. What *no one* had mentioned is that there is some sort of crappy little O-ring seal that essentially just popped out.
I am posting here so the next poor sod who googles "Dismantling AGA oil control valve" will find this post somewhere and be thereby illuminated.