Would this buttonhole attachment work on a Necchi BU (approx 1951) machine?
 

http://www.ebay.com/itm/NECCHI-sew-m...9#ht_610wt_935

I'm interested in buying it - but don't want to get stuck with something that wouldn't work on that machine - or worse yet, mess it up.

Does anyone know?

If your Necchi has a high shank it will NOT work. That is a low shank button holer.

If yours is the BU Nova, then yes. I have a Greist (which this is, according to the picture) that fits my BU Nova just fine. A low-shank Singer buttonholer works too, but on mine at least, it takes some wiggling and jiggling to get it to mate to the needle bar.