After countless hours of tinkering, we dropped the linkages.
So then the Eb" button and the D#" button on the right side play different pairs of reeds?
Also, out of curiosity, if one were to desire such an instrument but with the Hayden slanted rows, could it be made without too much extra work?
The Eb" and the D#" on the right side do indeed play different pairs of reeds.
And as far as making one with the rows in the Hayden slant, that's not something we could do without a prohibitive amount of extra work. It would require a total redesign of the lever arm locations, which would undoubtedly force us to move the reeds around, possibly forcing us to drop one or two. What we did was a major, major design project. In all the 30 odd years of my software life I never dealt with any project as mind-bogglingly complex, weird, frustrating and discouraging as getting the levers arms to run reasonably directly to their pads, given the limitation that the reeds should fit in a mere three dimensions. If I'd've had a fourth dimension, now.... (which is the nice thing about software: need another dimension? add one. Add six, if you need them. Sixty four, while you're at it; and let the computer keep track of them for you).
The beauty of the wedge shape of concertina reeds is that they fit in that nice radial pattern, so you get a lot of leeway in which to turn things this way and that. Accordion reeds are so big and rectangular, you don't have hardly any wiggle room, and that forces all kinds of weirdness on the rest of the instrument, unless you are willing to use short scale reeds, but even then (if you accept the musical compromise, and we really prefer not to) the short scale reeds don't help all that much. You just wind up with more little chunks of leftover space that you can't combine to fit another reed into.
If you come to the open house at the concertina workshop, I'll have my drawings for people to see; but I didn't keep the buckets of sweat and tears that Bob and I wept over them.