HP-97 missing keys

[Duane Hess]

I have removed all keys simply to clean them.

The cautious part of keyboard cleaning is the "backplate". I have been told the yellow markings is a type of ink. Depending on age (?) it can start to wipe off very quickly. Often I use dilute dishwashing liquid; i.e. same strength to wash dishes. 2-3 drops in 1/2 cup water. Or 50% Windex.

I rub on the keyboard but not on top of the yellow nomenclature. Rolling a Q-Tip over that area then rinse with clear water. I use the water faucet with a small stream. Then blot dry with paper towel or dish towel.

The entire backplate is coated after the yellow markings, which does wear off leaving that washed-out white appearance. If it is loose I rub it off & live with the results. If wear is light and doesn't come off I don't mess with it further.

Depending on dirtyness I have scrubbed with full strength Formula 409, Mean Green or dishwasing liquid (always with few drops water) with a toothbrush. But NEVER on top of the yellow markings. And avoid letting the liquids stand on the yellow markings. (or contact)

EDIT: I assume there are more fastidous folks than me and are much more cautious. And hopefully more knowledgeable. Sometimes living with the dirt seems the more likely alternative when considering longevity; maybe that's wrong.