Find out which part of the mechanism is responsible for the latching
action and fix it. This is the DIY group after all.

I thought it was also a forum for sharing knowldge. Hsaving looked, there
doesn't seem to be a latch or detent. I think something merely goes 'over-
centre'.
Hoped that someone had tried to fix this and wanted to share their
experience. It is fairly difficult to see how the parts react with each
other when it is turned over. Perhaps I need a 4-post lift!