I did some research on my storage bin recently, when my Cali came back from its roof job, and the bin began to lower itself every time a rough stretch of road was encountered.....this got to be a major pain, and did nothing for the rear view through the tailgate. It was also too easy to park and leave without realising that the contents of the bin were on display
The latch seemed to be grinding against the metal stop, and the filings were building up around the catch, causing a bit of a mess.
As far as I can see the catch is not available as a part, just the whole moving section of the bin in a piece.
There is some adjustment possible from above to the small metal catch, and I have moved this to reduce/minimise the small forward/backward play which the bin had when locked. I haven't road-tested it yet.
I think that this bin is one of the poorest features of the Cali, if the catch won't do its job, the addition of some form of back-up lock, etc is not easy, especially if you want it to look like "showroom" condition afterwards.
On the question of opening/closing, I have found that a hefty "straight arm tackle" is needed to close it, while opening is not as difficult, maybe a slight lift of the bin when pulling the catch.
I think VW assumed a wrestler-owner when designing the Cali, and especially furniture which must be moved regularly like sliding the bed, rotating the seats, especially the drivers side, raising and lowering the upper bed, and opening the storage bin. There must be a significant proportion of owners who have problems with these, or avoid using some features due to the effort needed?