In my house we have a central (“whole house”) vac, Daren, so the motor noise is down in the garage. There are outlets (inlets?) throughout the house, into which a 30′ hose plugs, and there are attachments for the other end of the hose. A melodica tuning attachment would need to have appropriately reduced or adjustable air flow. It looks like the reed plates would have to be removed to tune in this way, though.
The reed gapping seems to be done very quickly and in an unexpected way. During tuning, no support is provided for the reed, and not just the top surface of the reed is filed or scraped, but the sides and end as well. Also, the tuning is done in such a way that some of what appear to be variables in manually tuning one’s own melodica are ignored. For example, I get different readings on some keys depending on whether the Suzuki M-32C is in or out of its metal tray. Whether I’m using a mouth piece or not (and which kind of mouth piece) affects some readings at the low end. There’s some sense, I guess, in which the readings gotten with a mechanical device are the “true” measures of tuning.
I recognize the kinds of markings produced by whatever that device is with which the reeds are being scraped.
I’ll bet the equipment and processes are the same for Yamaha Pianicas. It would be interesting to see how those for generic Chinese melodicas and for the Hohners now made in China compare.