[Dirty Rooster]

I think all the corrosion was due to rust around the cowl hole aggravating the alloy beneath.
I got the circlip off with help from my wife : I used two hard steel strips bevelled to act as a circlip plier and she jammed a screwdriver in when a gap appeared.
Hammering and lubrication eventually got the rod out.
I sanded it inside and removed the rust from the rod, thing is really smooth now.
I'm going to ensure a good protection from water entering and check it every year.

Job done though!