If 'twer me, I'd arrange the chords thusly:

Top:      Gm Dm Am Em A
Middle:   C7 G7 D7 A7 E7
Bottom:   Bb F   C   G   D

You have a pattern of IV-I-V in the bottom row, but the key of A isn't easy (E7-A-D, in the same pattern) if the A is way off to the other end of the top row). Since you have the A chord, why not use it? The minor chords now fall in line with their relative major chords, although you may want to shift 'em off-line, to make chording easier. Since they're not in the same row as the majors, my assumption is there is a bit of an offset anyway, so you can probably handle them in their relative major keys.

As for the glue problem, I'd try a different kind of glue. Are these wooden, plastic, or aluminum chord bars? The difference will affect which glue would work best.

And the little flecks of felt will stop showing up about the time you need to replace the felt on the old, by-now worn bars.

The chord buttons should be as close to center as can be, since pressing off-center will result in inefficient transmission of the pressing force (one end will tend to stay up and the other go down too far).

That's all I can say now.

Bob Clayton