HI TEK Keyboard plungers?

[Martin.Hepperle at dlr.de]

Hello,

I have been servicing an HP 85A and an HP 85B desktop computer (printer belts, tape drive capstan). While the key caps of the "A" model are plugged into yellow plungers (according to the service manual the manufacturer is "STACKPOLE") the "B" came with white plungers ("Hi TEK" according to the svc. manual).
The yellow plungers were all in good condition, while several of the white plungers are split along one or two edges. I understand that this is a common problem with these HiTek keys.  The HP 85B suffers from this problem especially on the space bar which gets stuck when depressed.

So my question is: is there a way to repair (glue? melt?) these split plungers or are there replacement/alternative plungers available to replace the white HI TEK parts? I would need at least one (ideally more like 5) as the remaining broken plungers are still working. These keys seem to be used also in some VT100, DECWriter and even some Ti-99/4 keyboards.

If I cannot find a replacement, I would probably drill a lot of small holes into the plunger, glue it to the key cap, and then rework the outer dimensions so that it slides smoothly into the casing. But then I would probably not be able to remove the key caps later, after snapping it back into the casing - sort of one way fix with some risk.

Thank you for any recommendations,
Martin

--------------------------
Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)
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Dr.-Ing. Martin Hepperle | Aircraft Design and Configuration Aerodynamics
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