I have another idea here, inspired by the Suzuki MA-32 (1985-?) about which I posted under Vintage Melodicas recently. I pointed out that the MA-32 had, like some earlier Yamahas, its reed plates mounted facing down. This, though, is not the whole story. This Melodion was introduced by Suzuki as innovative because of its “cartridge” design. Cartridge is indeed the operative concept here. In disassembly, the reed chamber, including plates and reeds, is extracted after the removal of its four large screws. Here are some new photos plus one I posted earlier showing the reeds:
So here’s my suggestion, for which most of the credit has to go to Suzuki, of course: Use a cartridge design in our ideal melodica. Design the melodica in such a way that the cartridge can be snapped in and out, with a latching mechanism if necessary. Have replacement cartridges, alto and soprano, available at 50% (or whatever) of the cost of the whole melodica. For professional tuning or repair, require just submission of the cartridge
I hope to add to my earlier posting on the MA-32. My impressions of its sound are pretty favorable, but it is so far out of tune (incredibly sharp) that it needs work before I can make a fair assessment or post a sound clip. It seems to have a pleasing sound that differs from that of metal tray Suzukis. The MA-32 “Super II” is readily available at reasonable prices from Japanese auction sites.