Try HUTTON-ARCO Yacht Winches in Australia. They're expensive, but they are a reliable source of parts. I'm nursing 9 old Barients along, keeping then clean and greasy and hoping they live longer than I do.
They list an email on the site that they may not check all that often. If you have no luck with the email, call them -- they'll take a credit card number and put the parts in the post quickly.
Edit #2 -- Something funny is going on -- the post looks normal in the edit mode, but when I hit save it reverts to what you see here. It may be because the site has winches in the name and the SailNet store wants to sell me winches????????
I'll try one more time the site is www.arco-W.com/products/spares but where you see the W in the url type "winches" so it reads "arco dash winches dot com/products/spares"