When did HP retire their two-shot molded keys?

[jebem]

(03-05-2018 11:11 AM)BartDB Wrote:  Looking at that 31E, I doubt the original keys were worn away. My guess is they were deliberately repurposed and it is the repurposed lettering that has worn away. Perhaps carefully cleaning away the repurposing paint (or whatever material used) may reveal the original lettering.

That what I was thinking as well.
Although, not having the actual machine in your hand to check it, it is impossible to know from that picture what really happened.

Long time ago (late 70's) I worked for a consumer and telecommunications company that happened to also distribute HP calculators.
As such we had access to some scrap boards and spare parts that otherwise would end up in the garbage bin.
From those parts I could actually build one or two of my poor young man's HP calculators, but, guess what, I had some keys missing, so I have used physically identical keys and have used stickers over the key caps to to the correct labels on it.