I've messed a bit with the MCA's from the DX20 and KD50... turns out that the pump diode in the KD50 is shot, but its crystals seem okay. The diode still emits a fair amount of 808 light, but in 2 strips with a void in the middle.
I proceeded to put the kd crystal set in front of a DX20 pump, and it does produce some green. I couldnt find a really good spot (or didnt try hard enough), but as proof of principe it puts out a steady ~5 mW or so. I'm sure it could do better, but its pretty finicky to get things in place.
The DX has a collimating lens placed between pump diode and crystals, and a plastic spacer that makes things level between crystals and focal point of the collimated pump light. The KD has no such contraption and has the crystals directly on top of the pump diode, which seems easier to position in practice.
I wonder how these things are aligned in the factory, the mca is just glued in place. I guess it involves some device holding the mca steady with respect to the pump and adjusting for the optimum, after which glue is applied. Should be all that hard to rig something like that at home...