Thanks for being so sympathetic to my plight, but alas... no dice... (I shouldn't use that emoticon anymore, really).
I turned on the nunchuk-fix via composite but didn't get any video when I later switched to component. (unfortunately I can't get the menu to be displayed while using component cable - something that does seem to work with MegaDrive-games). I tried all three different display modes, and even fiddled with the widescreen settings for good measure.
I'm seriously thinking of 'downgrading' to RGB-component. I'm none too fond of the jagged edges in the regular Wii-games, so downgrading might provide a fix for that eyesore too. Has anyone on this forum done this, and if so, may we have your findings, please?
For that matter, has anyone on this forum tried to get Nintendo to replace their component cables by RGB-composite cables? And have you been succesful?