I have a (German built I believe) C Hohner one row four stop - so I think this is a HA114.
It seems to be generally flat (eg button 8 (G/F) is -60/-80 cents!). There is a small amount of corrosion on many of the reeds - would this account for much of the flatness? If so, then I guess I should remove this (wirewool/scotchbrite?) before considering individual reed tuning?
One of the reedblocks was lying loose in the case and so I have secured it temporarily by using some blobs of hot melt glue - this worked surprisingly well but I guess there must be air leaks as the base of the reed block is not sealed to the fondo. Given that these boxes are notoriously difficult to work on as the reed blocks are originally glued on, should I take the opportunity to convert it to a removable block design (a la Erica?) by fitting an olovisc gasket to the fondo and adding metal clamps (all available from CGM of course)?