I believe the fittings were supplied by the company that became NC Bjerg, unfortunately they went out of business and Ertec took over. They supply similar products but may have a minimum order. Details for Ertec are:
ERTEC DANMARK ApS.
EGESTEDVEJ 2B – DK-3320 SKÆVINGE – DENMARK
PHONE: +45 48 28 48 91 – FAX: +45 48 28 48 92
Another possibility is via the Hallberg Rassy spare parts web, as they use similar fittings to Nauticat, the link is below:
http://www.hr-parts.com/contents/en-us/d18.html
Or you may be lucky, Richard Wakeham, our Membership secretary had a bag of bits he bought from the USA,
which included some window catches, copy of picture of these attached.