On my car the catch slides between two Whitworth securing nuts and there is little tolerance. Due to wear or grit or angle of depression then the slider part hits the nut.
Lining up the nut flats with the slider helps.
I once changed the nuts to unf equivalent stainless....clunking and stuck every time. I once had to undo the catch receiver from the wing (nuts on underside!).
Hope this helps
