I love these too. I have the five screw piano 26 in pristine condition and it is one of my favourite hooters.
I am looking at the other later model Piano 26/27 in the alto 27 key version, having had some good results from
the similar even later model Piano 26 (Plastic body, made in Germany). The one I am looking at has the flat back which is screwed on, it’s blockier and larger than the older versions.
Currently attemping a rebuild and tune up of the similar five screw metal body piano 27 alto… wish me luck.