Obtained one of these locally and it's a bit of a mess cosmetically, in fact a lot of a mess.
Wrong soundbox and no gaskets at all.
But apart from that it's fine.
For starters, does anyone know what sort of wood is involved?
The correct soundbox for this model is the HMV No.2, but many machines of this era were later updated by their owners with a No.4.
This is easier to find than the No.2, especially on UK ebay, and will produce a better sound. If you can source an early brass backed example (the later ones are pot metal) it will be less difficult to dismantle for gasket replacement.
It came with a "Songster" soundbox bodged on with a piece of aluminium(?) pipe. The diaphragm is ripped and patched with tape, it has a cut & bent wood screw inserted to keep a needle in place... Really classy "repairs", not.
Had a spare Columbia soundbox which fits, so I was able to "test" it. I find it quite quiet, even allowing for the bodges, will a mica soundbox address this to a degree?
I have one of these in oak. The tonearm is different, a later type I think, more sinuous. The design around the Nipper Logo is absent also. And it has an HMV#4 soundbox. Otherwise it looks the same.