G'day Azure,
That's looks like a grub screw dog point. I can't see any issue with third party options.
Profurl are French , so it stands to reason it's metric. A pitch would most likely be 1.25 or 1mm.
If you haven't got any ability to measure pitch, take your other one to Bunnings and try it on a few different nuts to find out OD and pitch. You might get lucky and find there is only one pitch for that size

www.unitedfasteners.com.au/hexagon-socket-screws/socket-head-cap-screws-106/dog-point-socket-set-grub-screws.

Edit: I didn't check the link to see if their stainless, sorry, but it gets you started.
Edit edit: Loctite blue is a must for these things.

Call wichard pacific, the oz agent. I'm sure they are available and cheap

Brilliant! Thanks Bill, I think I'll be doing exactly the same.

I sailed with none and only worked out what the problem was after having furling problems in high winds. So should be OK with one or none for a short time.

Thanks Jack and Brett. I've been in contact with Wichard. Sent an email with pics on Friday night and got a response back on Saturday. They certainly are on the ball. I expect to have the parts in a few days.

Thanks everyone.