Thank you Michael and Gray…
Now I know what it's called,I've worked out what it does… It trips the feed if you drive it to the top…
The short pin is pushed up by the eye attached to the quill, and the toggle pushes the screwed rod down to trip the feed… (it's a toggle to reverse the direction…)
I've got about 1/2 of it out, after a lot of faffing with some ground down mosquito forceps…
I still can't get the rod out because the last bit of the toggle still jams it, got a 4mm Neodium magnet rod coming on Monday which hopefully will get it…

Michael, the nose piece has been butchered, prior to my ownership, and it seems was held in with araldite and the grub screw. I've built up the thread (looks like M74x1.25) with silicon bronze and will attempt to cut a new thread.
The spindle assembly (sadly) shows no sign of movement, but will keep trying…