HP-97 missing keys

[Duane Hess]

The hats can be pulled directly from the key "stem".

I have either worked on or cleaned 3(4?) HP-9x keyboards. The hats snap over the little "blob" you refer to as a heat stake. I don't know how the retaining "nub" is formed. But the hats can be rotated likely no heat staking is involved. Simply pull straight up to remove the hat. A rather small angle might be OK. It does take some effort. Not sure how to describe it but definately a noticeable force.

All parts being plastic sooner or later you will wear it out. But I have pulled a cap off & reinstalled 2-3 times with no noticeable deterioration (off & on is 1 time). In my opinion, you would wear the hat first. Most likely enlarging the hole (you'll notice the hat is the softer material). Even so, if it still stays on the stem I doubt any noticeable change in key action is likely.

At this point you should have 2 key stems/hats to practice on. The ones that were broken to begin with.