Thank you Custard.
The Ar 196 also initially had an issue with the engine mounting not being strong enough. When it collapsed the propeller would cut into the fuel tanks in the floats.That is what happens in the video, I believe.
The other issue I desribed seems only have to happened to the pilot of Graf Spee, so maybe he used a wrong landing technique - too flat? Does that make any sense? Certainly he had little experience as the type had been rushed into service.
Peter