Well I feel like a right idiot having to ask this but I cant recall where this part comes from on the furler, and the crane is booked for tuesday PM.

Its an original Profurl Proengin

I went through all my photos and cant see it anywhere. I dont recall seeing it before but it was in the furler box and fits perfectly around the aluminium tube. But no idea top/ bottom etc. Any ideas?

I finally found a pic with it in the parts and its positioned between top and bottom but still no idea what it's for.

Unfortunately it does. With it in place a separate repair I have done will need to be modified.

Its a sail feeder. goes on the bottom section of the furler, it can slide up and down a bit but I think there is usually a grubscrew into the furler to prevent it going up too far.
hope this helps