They don’t work
Cure: remove and replace with USA coupler with a modified one of course.
1: remove coupler and bracket
2: insert coupler upside-down in bracket, trim to expose mounting bracket holes, tap in for tight fit.
3: I used a USA talgo-mount coupler with some mod’s a: remove centring spring from shank. B:trim flush with to top and bottem lift pin and release from coupler.
4: reinstall bracket and install modifief coupler, do-not over tighten let it move side to side.
I did this over the weekend and it worked fine pulling 10 aristo reffer’s in a ABBA set up.