HP 67 programming?

[Helix]

I can't compare with the HP 41, but the keys of the two HP 67 I've found recently have small inconsistencies in their resistance. I don't know if this is due to heavy usage.

On these two calculators, when I received them, one row of keys was almost unresponsive: the top row for one, and the bottom row for the other. This was due to a plastic sheet that was worn and not perfectly aligned, so dust could go easily under the metallic strips.

A calculator with this defect can sometimes be purchased at a reasonable cost, and is not difficult to repair, if one accepts to damage the back label for opening the case. The dust can be removed with a strip of paper, and the plastic sheet is easy to replace with a new one.
These two videos will be better than my explanations:
https://www.youtube.com/watch?v=A22ZRju4wNc
https://www.youtube.com/watch?v=5AxjXCIew9I

And I can confirm that the red display of the HP 67 is really attractive!