Hi, in as much as I can tell I do not believe that it requires any non-cosmetic work.
Unfortunately the limit of my playing is to play a scale so I've done little more than kick the tyres.
However the bellows are extremely sound with no leaks and each of the 56 keys sound on both the in and out movements.
The left thumbstrap is sound but looks like it frayed and been repaired by Tom (this can be seen on the picture with the concertina in the box).