OP here -- So looks like I have two non-functioning keys that I trace to missing the shortish wire piece that connects the slug to the long piece that goes into the machine from the keytop. (I apologize for not knowing all the terms yet.) They are the "a" -- pretty crucial -- and the "@ / cents" key (not very). Still, I would like them to work, so this is now my repair task: either forming new bits -- pretty straightforward I think -- or scavenging them from a parts machine.
I may post photos tomorrow (it is at the office). But in the meantime, would you suspect the KH is close enough to the KMM to use the latter as a parts machine for it? i.e., these parts? Just considering my options -- though again, such a nondescript part I should be able to just handbend myself out of some wire.