Try some lock tight on the hinges.... just kidding.
With a magnet latch, sounds like the magnet may be too far from the metal it is connecting to. Try adjusting it closer, or loosening the screws to allow it to get closer.
My latch is a friction fit and seems to work fine. You could try changing it from a magnet to a friction latch.
'67 +4 tourer - broken white - RHD