Revelation suitcases are wonderful but a nightmare to fix as the catches are ridiculously complicated and often need to be split from the case.
The best suggestion for repair came from Bentleys of Walton Street, London, which specialises in vintage luggage and luxury accessories.
The company suggests scouring the country via eBay and auction websites for an old, damaged Revelation suitcase and using the fittings from that, though be warned: the fittings often varied from case to case.
Alternatively, contact a cabinet/watch/clock maker who might have the equipment and skills to dissect and repair such a catch or be able to make a new spring for it.